Propping doors open, such as fire rated doors, which normally are expected to remain closed when not in use with fire suppression devices, effectively reduce the use of these doors as fire or smoke barriers.
Fire doors are not allowed to be locked at any time when there are persons occupying the building.
One element of egress that is often overlooked is that portion of the exit discharge on the exterior of the building. The means of egress is required to extend without interruption to a public way. Make sure all means of egress are kept clear from plants, barriers or any other types of impediments.