FCOMP max fiber id only 999

Why does the Viavi  FCOMP module have a max fiber id of 999 for FiberComplete testing when the OTDR setup allows for a max fiber of 9,999?

Fiber id has to be communicated, between the two FCOMP units, over the fiber under test. A 4 number fiber id would take too long a transfer time so FCOMP is limited to a max fiber id of 999.