1| 2| 3| 4| 5| 6|What is an e-discovery load file? DAT, OPT, LFP and Bates numbers explained | LoadfileKit 7| 8| 9| 10| 11| 12| 13| 15|
16|
← LoadfileKit / Guides
17| 18|

What is an e-discovery load file?

19|

The index that ties a document production together

20| 21|

The short answer

22|

When one party produces documents in litigation, they do not hand over a bare folder of images. Alongside the TIFFs, natives and text files they include a load file: a plain-text index that tells the receiving party's review software what each document is, where its pages live, and how documents relate to each other. Without it a production is an undifferentiated pile of images; with it, a review tool rebuilds the document set, the metadata and the families.

23| 24|

Two kinds of file, and productions ship one of each

25| 26| 27| 28| 29| 30| 31|
Metadata load filesImage load files
Row granularityOne row per documentOne row per page
CarriesNamed fields — Bates ranges, custodian, correspondence, dates, extracted textImage key, volume, file path, document-break flag, page count
Common formatsConcordance DAT, CSVOpticon OPT, IPRO LFP
Looks like¶-delimited, þ-quoted records (DAT) or RFC 4180 (CSV)Seven comma columns (OPT) or IM command lines (LFP)
32|

The two describe the same documents from different angles, which is why converting between them means expanding a Bates range into page rows, or collapsing a page run back into a range — never losing the families on the way.

33| 34|

Bates numbers

35|

The unique page identifier stamped on every produced page: a fixed alpha prefix plus a zero-padded counter — ABC0001, SMITH-000123. A document spans the inclusive range from its BEGBATES to its ENDBATES; PAGECOUNT should equal the span. Because the whole system rests on that sequence, the classic pre-production check is a gap/duplicate audit: page ABC0007 missing between ABC0006 and ABC0008 means a page was dropped somewhere between imaging and export.

36| 37|

Document families

38|

An email and its attachments are separate documents that must review together. The convention: every family member carries a BEGATTACH (and usually ENDATTACH) equal to the parent's Bates range. Review tools group on it. A converter that reorders or splits rows without honoring it detaches attachments from their parent — a quality problem review teams find the hard way.

39| 40|

Why the delimiters look like noise

41|

Concordance DAT files use characters chosen to be absent from real text: the field delimiter is a control character (ASCII 20, commonly written ¶), the text qualifier is þ, and in-value line breaks are stored as ®. Open one with comma assumptions and you get a single garbled column. The DAT guide covers the grammar in detail.

42| 43|

What a conversion actually does

44|
    45|
  1. Parse the source with its own grammar — delimiters, qualifiers, break flags, @ tokens.
  2. 46|
  3. Model documents and pages neutrally: ranges for metadata, page runs for images, families keyed on BEGATTACH.
  4. 47|
  5. Serialize into the target grammar, re-deriving whatever the target needs that the source lacks (page counts from runs, ranges from keys).
  6. 48|
49|

Do it in the browser and the production index never leaves the machine. The converter does exactly this; the Bates checker audits sequences and cross-file consistency.

50| 51|

Questions

52|

What is the difference between a DAT and an OPT?

53|

A DAT is metadata — one row per document. An OPT is an image cross-reference — one row per page. A production usually includes both.

54|

Do I need expensive software to convert load files?

55|

No. The desktop suites cost four figures; the conversions themselves are deterministic text processing, and doing them client-side is enough. Free for small jobs, one-time license for larger ones.

56|

Can a load file be edited in Excel?

57|

Convert the DAT to CSV first — renaming the extension changes nothing, the delimiters are still control characters. Edit, then convert back.

58| 59|

More guides

60| 70| 71| 72|
73| 74| 75|