Is expiratory pressure relief similar to BiPAP on lower pressure settings?

[Gideon]

yes, and with AutoSet 'CPAP' up to 20/17

[Gideon]

The reason I was curious was that if it is the same option but in limited range, while would it be limited? Why cripple the option, if there is no difference on how the unit works.

Another reason is safety
A setting of 4-20 on a CPAP is pretty safe.  That is at most a PS of 3 applied om a sliding scale.

on a BiLevel the same 4-20 has been taken as EPAP of 4 and IPAP of 20 which means a PS of 16, a completely different story.  I've seen that mistake made by both AB members and Sleep Clinics setting a machine up that way.