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name: concordance description: Create a LibreOffice Writer concordance file (.sdi, semicolon-delimited) for use with the AutoMark feature to automatically generate a book index. Use when given text, a chapter, or a list of terms that need to be indexed. metadata: author: cascade version: "1.0" date: "2026-04-17"

Concordance File Skill

A concordance file is a semicolon-delimited text file used by LibreOffice Writer's Insert → Table of Contents and Index → AutoMark feature to automatically find and mark index entries throughout a document.

File Format

Each line is one index entry with six semicolon-separated fields:

Search term;Alternative entry;1st key;2nd key;Case sensitive;Word only

Field Reference

| Field | Required | Description | |---|---|---| | Search term | Yes | Exact text to find in the document | | Alternative entry | No | Text shown in the index (uses search term if empty) | | 1st key | No | Primary category / top-level index heading | | 2nd key | No | Secondary category for nested sub-entries | | Case sensitive | No | 1 = match case, 0 or empty = ignore case | | Word only | No | 1 = whole word only, 0 or empty = match substrings |

Example Lines

NetCDF;NetCDF;File Formats;;0;1
HDF5;HDF5;File Formats;;0;1
dispatch table;dispatch table;Architecture;;0;1
nc_open;;API functions;;0;1

How to Generate a Concordance CSV

Given source text (a chapter, section, or term list), follow these steps:

Step 1 — Identify Index-Worthy Terms

Extract terms that are:

• Proper nouns: product names, library names, standards (e.g., NetCDF, HDF5, Zarr)
• Technical terms: functions, data structures, algorithms, protocols
• Concepts: architecture patterns, design principles, key ideas
• Acronyms: with and without expansion (index both forms)
• People and organizations: authors, standards bodies

Avoid indexing:

• Common words (the, and, is, for)
• Terms appearing only once and not significant
• Overly generic terms that would produce hundreds of entries

Step 2 — Assign Categories (1st key)

Group related terms under a shared 1st key. Typical categories for technical books:

• API functions — function/method names like nc_open, nc_close
• Data structures — structs, classes, types
• File formats — NetCDF, HDF5, CSV, GeoTIFF
• Concepts — chunking, compression, dispatch
• Tools — command-line tools, utilities
• Standards — CF Conventions, OGC, ISO

For non-technical books, categories reflect subject matter:

• People, Places, Events, Terms, Organizations

Step 3 — Decide Case and Word Matching

• Use Word only=1 for most technical terms to avoid false matches (e.g., "var" matching "variable")
• Use Case sensitive=1 for proper nouns, acronyms, and function names
• Use Case sensitive=0 for concepts that may appear mid-sentence in lowercase

Step 4 — Write the CSV

Output as plain text, one entry per line, no header row, semicolons as delimiters:

Search term;Alternative entry;1st key;2nd key;Case sensitive;Word only

Save with .sdi extension in UTF-8 or ANSI encoding.

Complete Example

Given text about NetCDF file I/O, a concordance might look like:

NetCDF;NetCDF;File formats;;0;1
HDF5;HDF5;File formats;;0;1
Zarr;Zarr;File formats;;0;1
nc_open;nc_open();API functions;;1;1
nc_close;nc_close();API functions;;1;1
nc_get_vara;nc_get_vara();API functions;;1;1
dispatch table;dispatch table;Architecture;;0;1
NC_Dispatch;NC_Dispatch;Data structures;;1;1
chunking;chunking;Concepts;;0;1
compression;compression;Concepts;;0;1
OPeNDAP;OPeNDAP;Protocols;;1;1
DAP2;DAP2;Protocols;;1;1
DAP4;DAP4;Protocols;;1;1

Output Format Rules

1. No header row in the output file — LibreOffice expects data on every line
2. Semicolons as delimiters (not commas)
3. No quotes around fields unless the field contains a semicolon
4. One entry per line
5. Sort alphabetically by search term for readability (optional but helpful)
6. UTF-8 encoding for documents with non-ASCII characters

Tips

• A term can appear multiple times under different 1st keys if it belongs to multiple categories
• The Alternative entry can be used to normalize capitalization in the index (e.g., search hdf5, display HDF5)
• For acronyms, add two entries: one for the acronym, one for the expanded form, both pointing to the same 1st key
• Keep 2nd key sparse — only use it when a category genuinely has sub-groupings (e.g., 1st key API functions, 2nd key read vs write)