DAT file
A DAT file is the delimited text file in a document production that carries each document's metadata, one row per document, with fields such as beginning and ending Bates number, custodian, dates, subject and file path in an agreed order. It is read by the receiving review platform to rebuild the production's structure.
Also called: delimited load file · metadata load file · Concordance DAT
Updated September 6, 2026
How does a DAT file work?
The DAT file is the document-level index of a production. Every row is one document; every column is one metadata field the parties agreed to exchange. Because ordinary characters like commas and quotation marks appear constantly in email subjects and file names, the format uses delimiters that almost never occur in real content. The first row is a header naming the fields.
Encoding matters as much as delimiters. A DAT file written in UTF-8 and read as ANSI, or vice versa, corrupts every non-ASCII character, and the delimiters themselves sit above the ASCII range, so the failure is often total rather than cosmetic. The ESI protocol should state both.
What does a DAT file look like in practice?
Header and one row, delimiters shown literally:
þBEGBATESþ¶þENDBATESþ¶þBEGATTACHþ¶þENDATTACHþ¶þCUSTODIANþ¶þDATESENTþ¶þSUBJECTþ¶þNATIVELINKþ
þSMITH-000148þ¶þSMITH-000151þ¶þSMITH-000148þ¶þSMITH-000152þ¶þMendez, Janeþ¶þ2024-03-11þ¶þRe: Q1 forecastþ¶þ\NATIVES\SMITH-000148.xlsxþA DAT that fails to import is the most common production defect; the production checklist covers the delimiter, encoding and field-order checks that catch it.
How does a DAT file show up on an eDiscovery invoice?
The DAT file is generated as part of a production export, so it is priced inside whatever production or export fee the provider charges, usually per gigabyte. Requests for a non-standard field order, an extra field, or a re-export after a correction are where hourly project management charges tend to appear. Ask whether custom field configurations are included and whether a re-production is billed as a new production.
Sources
- EDRM production and load-file guidance.
- The Sedona Conference Glossary, “load file.”
Related terms
eDiscovery at one flat monthly rate
$3,250 a month on a 12-month agreement. No per-user fees and no per-GB hosting charges.
Common questions
What delimiters does a DAT file use?
The Concordance defaults, which most platforms adopt: þ (ASCII 254) as the text qualifier around each value, ¶ (ASCII 020) as the field separator, and ® (ASCII 174) to stand in for line breaks inside a value. The parties can agree others, but changing them without telling the receiving side is the most common load failure.
What fields go in a DAT file?
Whatever the ESI protocol specifies. A typical set includes BEGBATES, ENDBATES, BEGATTACH, ENDATTACH, CUSTODIAN, ALLCUSTODIANS, FROM, TO, CC, BCC, SUBJECT, DATESENT, TIMESENT, DATECREATED, DATELASTMODIFIED, FILENAME, FILEEXTENSION, HASHVALUE, NATIVELINK, TEXTLINK, CONFIDENTIALITY and REDACTED.
Can I open a DAT file in Excel?
You can, but carefully. Excel will not recognize the þ and ¶ delimiters automatically and can silently reformat dates and Bates numbers. Open it as a delimited text import with the delimiters set explicitly, or inspect it in a plain-text editor.