File ID
Each file assigned to the workspace has a file identifier.

Rigi uses this file ID to construct a unique Rigi identifier. For example, if the file ID is en, the string ID for each string in that file starts with en.

File IDs are also present in HTML previews.
Warning
Once assigned, IDs must not be changed. If they are changed, strings in HTML previews and in the project might no longer match.
File splitting
When developers split a file into two parts (with strings present in captured HTML previews), you should assign both files the same file ID.
Mass rename
If a project contains many files, you might find it useful to use the file ID mass rename feature. For details, see the Mass rename file IDs guide.