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Finding Schematics and Board Diagrams

The last section named the three documents and promised this one would teach the hunt in full — because for board-level repair, a found schematic is worth more than any single instrument on the bench, and finding one is a searchable skill rather than luck. The hunt runs on an identifier chain: the retail name on the box unlocks the internal model code, the internal code unlocks the board number printed on the motherboard's silkscreen, the board number unlocks the ODM project name that the real documentation indexes by, and the platform name — the chipset family under everything — unlocks reference designs when the exact board cannot be found. Each link in that chain opens sources the previous link could not. Then the source landscape itself: official publication and right-to-repair disclosures at the top of the provenance ladder, board-repair communities and their archives in the working middle, forum attachments and paid databases below, and the donor board as the physical document that answers questions no PDF can — with provenance recorded on the sheet, because where a document came from decides how much to trust its revision. Then the skill that makes the found document useful: reading an unfamiliar schematic, which differs from Volume 1's idealized pages the way a real city differs from a subway map — orientation via the block diagram and power-tree pages, manufacturer rail-naming schemes decoded, nets followed across sheets by their labels, and connector sheets used as the bridges they are. Then the pairing that turns paper into bench work: schematic plus boardview yielding test-point maps and the margin-column numbers the universal tree runs on. And finally the honest fallback: working without, when the hunt fails — the donor board, the traced net, the known-good reference — and publishing the bench's own findings back, because every schematic you could not find is a gap some future bench will thank you for filling. By the end, the document hunt is a fifteen-minute procedure with recorded results either way — and the found schematic goes to work the same afternoon.

IntermediateLow Risk20 min read

What You Will Learn

  • You will learn the identifier chain — retail name to internal model to board number to ODM project to platform — and what each link unlocks.
  • You will learn the source landscape — official disclosure to community archives to paid databases to donor boards — with provenance recorded.
  • You will learn to orient in an unfamiliar real schematic — block diagram and power-tree pages first, rail-naming schemes decoded, nets followed across sheets.
  • You will learn to pair schematic and boardview into bench assets — test-point maps and the margin-column numbers the universal tree runs on.
  • You will learn to work without the documents — donor boards, traced nets, known-good references — and to publish findings back.

What You Will Be Able To Do

  • You will be able to build the identifier chain — retail name to internal model to board number to ODM project to platform — and use each link's unlocks.
  • You will be able to hunt across the source landscape — official disclosure to community archives to paid databases to donor boards — recording provenance.
  • You will be able to orient in an unfamiliar real schematic — block diagram and power-tree pages first, rail names decoded, nets followed across sheets.
  • You will be able to pair schematic and boardview into bench assets — test-point maps and margin-column numbers for the universal tree.
  • You will be able to work without the documents — donor boards, traced nets, known-good references — and publish findings back.

Required Tools

  • An internet-connected computer and patience for the hunt
  • The device's real identifiers, or the device itself to find them
  • A boardview viewer application for the files the hunt returns
  • An unfamiliar real-world schematic to practise orientation on
  • The pre-open sheet, whose documents field this section fills

Section Overview

The last section named the three documents; this one teaches the hunt in full and the reading that follows, because a found schematic outranks any single instrument on the bench (research-before-you-open-the-device). The hunt runs on an identifier chain. Retail name unlocks internal model, internal model unlocks the board number on the silkscreen, the board number unlocks the ODM project name that real documentation indexes by, and the platform name unlocks reference designs when the exact board cannot be found — each link opens sources the previous could not. The sources form a provenance ladder. Official publication and right-to-repair disclosure at the top, board-repair communities in the working middle, forum attachments and paid databases below — with origin recorded on the sheet, because provenance decides how much to trust a document's revision match. Unfamiliar schematics have an orientation ritual. The block diagram and power-tree pages first, the manufacturer's rail-naming scheme decoded, nets followed across sheets by their labels — real pages read differently from Volume 1's idealized ones, but with the same grammar (reading-a-complete-schematic). Paper becomes bench assets. Schematic plus boardview yields test-point maps and the margin-column numbers the universal tree runs on — the found document works the same afternoon (the-universal-tree-power-heartbeat-path). And absence has a workflow. Donor boards, traced nets, and known-good references stand in when the hunt fails — and the bench publishes its own findings back (schematic-symbols-and-conventions). Chain, ladder, orientation, pairing, and the fallback — the document hunt is a procedure, not luck.

Why This Matters

Board-level repair without documents is archaeology; with them it is reading — and the difference is usually fifteen minutes of disciplined hunting (research-before-you-open-the-device). This matters because the chain is where hunts die: most failed searches fail at the first link — hunting the retail name against archives indexed by board numbers and ODM projects — and the technician concludes the schematic does not exist when only the search term was wrong. This matters because provenance is a correctness question: boards revise, and a schematic for the wrong revision confidently names test points that moved — recording where a document came from and which revision it claims is what keeps paper from contradicting copper (schematic-symbols-and-conventions). It matters because real schematics are navigable once oriented: forty sheets intimidate until the block diagram and power tree turn them into a map — the orientation ritual is minutes, and it converts the document from decoration to tool (reading-a-complete-schematic). It matters because the margin column is waiting: Volume 5's universal tree runs on rail names and expected voltages, and the found schematic fills that column in one sitting — the single highest-leverage transfer from paper to bench (the-universal-tree-power-heartbeat-path). And it matters because the community's archives are made of contributions: every traced net and measured reference the bench publishes back is the schematic some future technician finds — the hunt's ecosystem runs on benches that give as well as take. Learn the hunt as a procedure, and the bench stops doing archaeology on documented boards.

Required Prerequisites

  • Research Before You Open the Device — Section 1.1 placed the document hunt in the desk stage and its results on the pre-open sheet; this section is that hunt taught in full.
  • Reading a Complete Schematic — Volume 1 taught schematic reading on idealized pages; this section applies that grammar to real manufacturer documents with their own conventions and sprawl.
  • The pre-open sheet's documents field — to land every finding and every recorded absence with its date (research-before-you-open-the-device)
  • A links file per model — to keep found sources findable when the family's next unit arrives
  • A provenance column beside every link — to record origin and claimed revision, because trust is graded
  • A rail-name cheat sheet, built as you decode — to turn one schematic's naming scheme into the family's reference (the-universal-tree-power-heartbeat-path)
  • A donor-board budget line — to treat the physical document as the purchasable option it is
  • A laptop or console with visible board silkscreen — to practise the identifier chain on real markings (research-before-you-open-the-device)
  • A boardview viewer with a sample file — to practise net lookup before a case depends on it
  • One unfamiliar real schematic, any mainstream laptop — to run the orientation ritual on genuine sprawl (reading-a-complete-schematic)
  • A known-good board of any documented model — to check paper against copper and calibrate revision trust
  • The bench's universal tree with an empty margin column — to practise the paper-to-bench transfer (the-universal-tree-power-heartbeat-path)
  • A folder of the bench's own traced notes — to see what publishing back would look like

Real-World Applications

The hunt's discipline shows up as documents found where others gave up. A technician whose search for a laptop's retail name returns nothing flips the board, reads the ODM project code off the silkscreen, and finds schematic and boardview both on the first community search — the chain's third link where the first had failed (research-before-you-open-the-device). A repairer with a found schematic checks its claimed board revision against the silkscreen before trusting a single test point — and catches that the archive's file is one revision old, with the charging circuit redrawn since (schematic-symbols-and-conventions). Someone opening a forty-sheet schematic for the first time goes straight to the power-tree page, decodes the naming scheme from three rails, and has the whole document navigable in ten minutes (reading-a-complete-schematic). A bench pairing schematic and boardview for a dead console produces a one-page test-point map for the main rails before the board is even unscrewed — and fills the family's margin column in the same sitting (the-universal-tree-power-heartbeat-path). And a technician who traced an undocumented power rail by hand posts the annotated photos to the model's community thread — the next bench's found document, and the bench's name on it. The failures this prevents: a schematic declared nonexistent because the retail name was the only search term, test points trusted from a wrong-revision document, forty sheets abandoned as unreadable, and a found PDF that never becomes a single bench measurement.

Common Challenges

  • The chain's links hide in different places. Internal codes live on regulatory labels, board numbers under RAM or heatsinks, ODM names in BIOS strings — the difficulty is knowing the hiding places, and this section's list is the map (research-before-you-open-the-device).
  • Naming schemes differ by manufacturer. One vendor writes PP3V3_S5 where another writes +3V_S5, while a third's main switched rail is VCC3M — same grammar, different dialects and power states — the difficulty is decoding scheme logic from a few examples rather than memorizing every vendor's dialect (reading-a-complete-schematic).
  • Provenance is invisible in a PDF. A confident-looking schematic carries no badge saying which revision it matches — the difficulty is the verification habit: check the document's claimed board number against the silkscreen before trusting, every time (schematic-symbols-and-conventions).

Safety Notes

Risk Level: Low. This section is desk work and document reading — its safety content is the correctness discipline that keeps paper from misdirecting hands later.

Professional Tips Before Starting

  • Build the whole chain before searching. Five identifiers noted first beats five searches improvised — retail, internal, board, ODM, platform, then hunt (research-before-you-open-the-device).
  • Decode the naming scheme from the power tree. Three rails' names usually reveal the whole scheme's logic — suffix for power state, prefix for source, number for voltage (reading-a-complete-schematic).
  • Verify one rail before trusting forty sheets. A single measured voltage matching the schematic's claim buys the document its credibility — cheap, fast, and habit-forming (the-universal-tree-power-heartbeat-path).

The Hunt and the Reading — Chain, Ladder, Orientation, Pairing, Fallback

Recap and Frame

Section 1.1 put the documents on the pre-open sheet; this section is the two skills behind that field: finding the documents, and making found documents work (research-before-you-open-the-device). The hunt is a procedure with a chain. Searches fail at wrong terms far more often than at missing documents, so the procedure builds the full identifier chain first and spends each link against the sources it unlocks. Trust is graded by origin. The provenance ladder runs from official disclosure to grey archives, and the grade travels with the document onto the sheet — because the reading that follows will stake real measurements on the paper's claims (schematic-symbols-and-conventions). Reading real documents is Volume 1's grammar at scale. The symbols and conventions transfer; what is new is sprawl — forty sheets, vendor naming dialects, and navigation by net label — and the orientation ritual tames all three (reading-a-complete-schematic). The destination is the bench. Every found document is converted to bench assets the same day: the test-point map for this case, the margin column for the family's tree (the-universal-tree-power-heartbeat-path). And the fallback is part of the procedure. When the hunt fails, the donor board and the traced net stand in — and the bench's own tracing becomes the community's next document. Hold the frame — chain before search, trust by origin, grammar at scale, paper to bench, fallback included — and the hunt becomes a fifteen-minute procedure with recorded results either way.

Every document hunt starts by building the chain, because each identifier unlocks sources the others cannot (research-before-you-open-the-device). The retail name is only the first key. The name on the box finds teardown guides and community threads — and, crucially, the places where the deeper identifiers are photographed and listed. The internal model code narrows the family. On the regulatory label, inside the battery compartment, or in the settings menu — the internal code separates the three hardware variants that share one retail name, and manuals index by it. The board number is the silkscreen's gift. Printed on the motherboard itself — sometimes under RAM, shields, or heatsinks — the board number is what schematics and boardviews actually index by, and photographing it during any opening pays forward. The ODM project name unlocks the real archives. Many devices are designed by original design manufacturers whose project names — not the brand's — title the engineering documents; the ODM name surfaces on the silkscreen, in BIOS strings, or in the community's cross-reference threads (schematic-symbols-and-conventions). The platform name is the last resort that often works. The chipset platform under the board has reference designs and platform design guides — not this board's schematic, but the circuit its designers started from, which makes an undocumented board far more readable (reading-a-complete-schematic). Retail to internal to board to ODM to platform, each noted before the search begins — the chain is the hunt's ammunition. Build all five links first, and the search stops dying at its first term.

The Source Landscape — A Ladder with Provenance

The sources arrange into a ladder, and where a document came from decides how it is treated (research-before-you-open-the-device). Official disclosure tops the ladder. Manufacturer-published manuals and the growing body of right-to-repair disclosures carry the best revision fidelity — searched first, trusted most, and still verified. Board-repair communities are the working middle. The forums and archives where board-level repair actually lives hold the deepest schematic and boardview collections, indexed by board number and ODM project — quality is high, revision labeling varies, and verification is standard practice. Forum attachments and paid databases fill gaps. One-off uploads and subscription libraries surface documents the archives lack — provenance is thinner, so the verification bar rises with them. The donor board is the physical document. A cheap donor answers questions no PDF can — the actual layout, the actual values, and — if it powers — a known-good reference for every rail; for undocumented models it is often the best money in the case (the-universal-tree-power-heartbeat-path). Provenance is recorded, not remembered. Every found document lands on the sheet with origin, claimed board number, and the date — because the family's next case will read this field before trusting the link (schematic-symbols-and-conventions). Legitimacy gets its honest sentence. The landscape ranges from published to grey; the bench prefers official sources where they exist, notes what it uses, and contributes its own work back to the open side of the ledger. Official first, communities as the working core, gaps filled warily, the donor as truth, and provenance on the sheet — that is the landscape. Climb the ladder from the top, and record where each rung came from.

Orientation — Reading a Real Manufacturer Schematic

A real schematic differs from Volume 1's teaching pages in scale and dialect, not grammar — and orientation converts sprawl into a map in minutes (reading-a-complete-schematic). The block diagram is the front door. Most manufacturer schematics open with a block diagram and a sheet index — one page that says what lives where, read before anything else. The power-tree page is the bench's home page. Real schematics dedicate pages to power generation and distribution — every rail, its source, and its enable — and Volume 5's power-first method makes this the page the bench works from most (the-universal-tree-power-heartbeat-path). Rail names follow decodable schemes. Vendor dialects differ — prefixes for permanence, suffixes for sleep states, numbers for voltage — but three examples from the power tree usually reveal the scheme's logic, and the decoded scheme reads the whole document. Nets travel by label. A net leaving one sheet continues wherever its label appears — the cross-sheet navigation that replaces Volume 1's single-page wiring, with the boardview or the PDF's search as the index (schematic-symbols-and-conventions). Connector sheets are the bridges. Every cable, flex, and socket has its sheet — pinouts that turn "which pin is the backlight enable" from guesswork into a lookup, and the first stop for any harness-related fault. Reference designators tie paper to copper. The schematic's C4021 is the board's C4021 — matched through the silkscreen where it carries designators, and through the boardview where dense modern boards omit them — the thread the next subsection's pairing pulls. Front door, home page, decoded dialect, labeled travel, bridge sheets, and designators as the thread — orientation is a ritual of minutes. Orient before reading, and forty sheets become one navigable document.

The Pairing — From Paper to Test Points and Margins

A schematic answers what; the boardview answers where; paired, they produce the two assets every case wants (the-universal-tree-power-heartbeat-path). Net lookup is the pairing's engine. Pick the rail on the schematic, search its net name in the boardview, and every pad carrying it lights up — the hour of continuity tracing that Volume 5 budgeted for undocumented boards collapses into a lookup. The test-point map is the case asset. For the complaint at hand: the suspect rails, their most accessible pads — test points where the designer provided them, component pads where not — marked on one printed page before the board is opened (research-before-you-open-the-device). The margin column is the family asset. Rail names and expected voltages from the power tree, transcribed into the universal tree's margin column in dated pencil — the single sitting that turns Volume 5's spine from generic to family-fluent. Verification buys the trust. Before either asset directs hands: the document's board number against the silkscreen, and one known rail measured against its stated voltage — paper earns credibility one confirmed claim at a time (schematic-symbols-and-conventions). The assets file with the family. Test-point map and margin numbers land in the family library beside the document links — the model's next case starts with both already printed (reading-a-complete-schematic). Lookup as the engine, a map for the case, margins for the family, trust bought by verification, and everything filed — the pairing is paper going to work. Convert the document the day it is found, and the hunt's minutes repay themselves the same afternoon.

Working Without — The Fallback and the Gift Back

Some hunts fail honestly, and the bench that knows the fallback works almost as fast (research-before-you-open-the-device). The absence is recorded first. "No schematic, no boardview as of this date, all five identifiers tried" goes on the sheet — the finding that saves the family's next case the same hour. The donor board becomes the document. A known-good donor answers layout, values, and voltages by measurement — every reference the schematic would have stated, read from copper instead — and doubles as the parts shelf (the-universal-tree-power-heartbeat-path). The platform's reference design approximates. The chipset's design guide describes the circuit this board's designers adapted — rail structure, sequencing, controller choices — close enough to orient diagnosis even where details differ (reading-a-complete-schematic). Tracing rebuilds the local map. Volume 5's methods — continuity from the suspect area, the injection and tracing chapters' techniques — reconstruct the nets that matter for this fault, and the reconstruction is written down as it happens. The bench's notes become the next bench's document. Annotated board photos, traced nets, measured references — published to the model's community thread, they are exactly the document some future hunt will find; the archive the bench searches is made of benches that did this (schematic-symbols-and-conventions). Absence filed, donor as truth, platform as approximation, tracing as reconstruction, and the notes given back — working without is slower, not blind. When the hunt fails, document as you go — for the case, the family, and the commons the next hunt searches.

Common Mistakes

  • Searching only the retail name. Archives index by board number and ODM project — build the whole identifier chain before concluding a document does not exist (research-before-you-open-the-device).
  • Trusting an unverified revision. Boards revise and archives lag — check the document's claimed board number against the silkscreen, and measure one known rail, before paper directs hands (schematic-symbols-and-conventions).
  • Reading sheets in order. Page one to page forty is the slow way into a real schematic — block diagram, then power tree, then the sheets the fault names (reading-a-complete-schematic).
  • Leaving the found document as a PDF. Paper that never becomes a test-point map or a margin column changed nothing at the bench — convert it the day it is found (the-universal-tree-power-heartbeat-path).
  • Taking without giving back. The archives are made of contributed traces and notes — publish what the bench reconstructs, because the commons is the next hunt's source.

Troubleshooting Guidance

The hunt runs chain, ladder, orientation, pairing, fallback. If the search returns nothing: check which link you searched with — most dead hunts used the retail name against archives indexed by board number and ODM project (research-before-you-open-the-device). If the board number is not visible: look under RAM, shields, and heatsinks during any opening, and photograph it for the family file. If a document is found: record provenance and claimed revision on the sheet, then verify — board number against silkscreen, one rail against its stated voltage (schematic-symbols-and-conventions). If the schematic sprawls: run the orientation ritual — block diagram, power tree, naming scheme from three rails — before reading anything else (reading-a-complete-schematic). If a rail name resists decoding: find it on the power-tree page where its source and voltage make the name's logic visible. If schematic and boardview are both in hand: convert same-day — test-point map for the case, margin column for the family's tree (the-universal-tree-power-heartbeat-path). If the hunt honestly fails: record the absence with its date, price a donor, lean on the platform's reference design, and trace what the fault needs — writing it down as you go. If you reconstructed anything: publish it to the model's thread — the commons that failed you is the commons you just improved. The throughline: build the chain, climb the ladder from the top, orient before reading, convert paper to bench assets the same day, and give the reconstruction back.

Verification & Testing Methods

Confirm the hunt is a procedure in your hands, not a hope:

  • [ ] I build the identifier chain before searching — retail name, internal model, board number from the silkscreen, ODM project, platform name — and I can say which sources each link unlocks.
  • [ ] I climb the source ladder from the top — official disclosure, community archives, gap-fillers, donor board — and every found document lands on the sheet with provenance, claimed revision, and date.
  • [ ] I verify before trusting: the document's claimed board number against the silkscreen, connector counts against the physical board, one known rail measured against its stated voltage — with safety-relevant fields never taken from a single unverified source.
  • [ ] I orient in an unfamiliar schematic as a ritual — block diagram, power-tree page, naming scheme decoded from three rails, nets followed by label, connector sheets as bridges — and I convert found documents same-day into a test-point map and the family's margin column.
  • [ ] I work without documents deliberately when the hunt fails — absence recorded with its date, donor board as the physical reference, platform design guide as the approximation, traced nets written down as reconstructed — and I publish the reconstruction back to the model's community.

Then try the practice exercises below — desk and paper work; scenarios differ from the quiz.

Practice Exercises

  1. Build a chain (5 minutes, desk). For a real device on hand, collect all five identifiers — retail name, internal model code, board number (photograph the silkscreen if the device is already open or the label shows it), ODM project if discoverable, platform name — and note where each was found (research-before-you-open-the-device).
  2. Climb the ladder, and plan the fallback (5 minutes, desk). Hunt the chain's identifiers across at least three source tiers, and record on a sheet what each tier returned — including empty results — with provenance and dates for anything found; for whatever was not found, write the fallback plan — a donor unit priced, the platform or controller-vendor reference design identified — and draft the one-line publish-back note describing what this bench would contribute to the model's thread after tracing (schematic-symbols-and-conventions).
  3. Run the orientation ritual (5 minutes, paper). Open any unfamiliar real schematic, find the block diagram and power-tree pages, decode the rail-naming scheme from three rails, and follow one net across two sheets by its label (reading-a-complete-schematic).
  4. Convert to bench assets (5 minutes, paper). From a schematic-boardview pair — or the orientation exercise's schematic alone — produce a five-point test-point map for an imagined dead-rail complaint and a margin-column entry (three rail names with expected voltages) for the family's universal tree (the-universal-tree-power-heartbeat-path).

These core steps — the chain, the ladder with provenance, the orientation ritual, the same-day conversion, and the honest fallback — are tested in the Chapter Quiz at the end of this chapter, where a score of 80% is required to continue.

Key Takeaways

  • The hunt runs on the identifier chain — retail name to internal model to board number to ODM project to platform name — built in full before searching, because most dead hunts used the wrong term against archives indexed by the deeper links (research-before-you-open-the-device).
  • Sources form a provenance ladder — official disclosure, community archives, gap-fillers, the donor board as the physical document — with origin, claimed revision, and date recorded on the sheet, because paper earns trust by verification: board number against silkscreen, one rail against its stated voltage (schematic-symbols-and-conventions).
  • Real schematics are Volume 1's grammar at scale, tamed by the orientation ritual: block diagram first, the power-tree page as the bench's home page, rail-naming schemes decoded from three examples, nets followed across sheets by label, connector sheets as the bridges (reading-a-complete-schematic).
  • Found documents convert same-day into bench assets: the schematic-boardview pairing's net lookup produces the case's test-point map and the family's margin-column numbers — the single highest-leverage transfer from paper to the universal tree (the-universal-tree-power-heartbeat-path).
  • Failed hunts have a workflow: the absence recorded with its date, the donor board as measured truth, the platform's reference design as approximation, traced nets written down as reconstructed — and the reconstruction published back, because the archives the bench searches are made of benches that gave.

Skills Learned

  • You can now build the identifier chain — retail name to internal model to board number to ODM project to platform — and use each link's unlocks.
  • You can now hunt across the source landscape — official disclosure to community archives to paid databases to donor boards — recording provenance.
  • You can now orient in an unfamiliar real schematic — block diagram and power-tree pages first, rail names decoded, nets followed across sheets.
  • You can now pair schematic and boardview into bench assets — test-point maps and margin-column numbers for the universal tree.
  • You can now work without the documents — donor boards, traced nets, known-good references — and publish findings back.

Glossary Additions

  • board number — the identifier printed on a circuit board's own silkscreen — sometimes hidden under RAM, shields, or heatsinks — that engineering documents actually index by: schematics and boardviews are filed under board numbers, not the retail name on the device's box. The board number is the hunt's most valuable link because the revision is printed beside it: a document whose claimed board number matches the silkscreen exactly, revision included, has passed the first trust test, while a near-miss means the paper may confidently describe test points and circuit details that moved. Photographing the board number during any opening pays forward — it is the identifier the family's next document hunt will need first.
  • ODM — an original design manufacturer: a company that designs and builds devices sold under other brands' names, common in laptops and widespread across consumer electronics. ODMs matter to the document hunt because the engineering documentation — schematics, boardviews — is titled by the ODM's own project names rather than the brand's retail names, so a search that knows the ODM project code unlocks archives the retail name never will. The ODM project name surfaces on the board's silkscreen, in firmware and BIOS identification strings, and in the repair community's cross-reference threads that map retail models to the projects behind them.
  • platform name — the name of the chipset platform a board is designed around, and the document hunt's last resort that often works: when a specific board's schematic cannot be found, the platform's reference design and design guide describe the circuit the board's designers adapted — the rail structure, power sequencing, and controller arrangement — close enough to orient a diagnosis even where component-level details differ. Platform documentation comes from the chipset vendor's ecosystem and is indexed by platform codename, making it findable even for obscure devices; read alongside the physical board, it turns an undocumented layout from archaeology into a guided reconstruction.

Suggested Next Sections

Must read next:

  • Photographing the Device Before Disassembly — Section 1.3 turns to the record the bench makes for itself: the photographic discipline — overview to detail, every connector before it opens, every screw beside its hole — that makes reassembly a matter of record rather than memory.

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