NewRevision sets the optional parameter "newRevision": Whether a blob upload should create a new revision. If false, the blob data in the current head revision is replaced. If true or not set, a new blob is created as head revision, and previous unpinned revisions are preserved for a short period of time. Pinned revisions are stored indefinitely, using additional storage quota, up to a maximum of 200 revisions. For details on how revisions are retained, see the Drive Help Center.