For extended status, select the files on which to report status.

• GIT_STATUS_SHOW_INDEX_AND_WORKDIR is the default. This roughly matches git status --porcelain where each file gets a callback indicating its status in the index and in the working directory.
• GIT_STATUS_SHOW_INDEX_ONLY only gives status based on HEAD to index comparison, not looking at working directory changes.
• GIT_STATUS_SHOW_WORKDIR_ONLY only gives status based on index to working directory comparison, not comparing the index to the HEAD.
• GIT_STATUS_SHOW_INDEX_THEN_WORKDIR runs index-only then workdir-only, issuing (up to) two callbacks per file (first index, then workdir). This is slightly more efficient than separate calls and can make it easier to emulate plain git status text output.