Glossary
Known folder GUID (KNOWNFOLDERID)
A GUID that Windows uses to name a standard folder such as System32 or Program Files. Timeline AppId paths often start with one instead of a drive letter.
Windows identifies standard folders by KNOWNFOLDERID constants (Microsoft Learn). In ActivitiesCache.db, application paths often begin with one: {1AC14E77-02E7-4E5D-B744-2EB1AE5198B7} is System32, {6D809377-6AF0-444B-8957-A3773F02200E} is the 64-bit Program Files, {7C5A40EF-A0FB-4BFC-874A-C0F2E0B9FA8E} is Program Files (x86).
Because the GUID does not record a drive letter, the Windows Timeline Parser renders it as an environment variable such as %ProgramFiles%. See activity types and payload fields.