Hi Andrew, you can find the information below in 16.1 User Guide:
PIM Edge Mode is a subset of PIM that operates with the following restrictions:
- The switch does not act as a candidate rendezvous point (CRP).
- The switch does not act as a candidate bootstrap router (CBSR).
- At most, four active PIM-SM interfaces are permitted. There is no restriction on the number of
passive interfaces (within the limit of the maximum IP interfaces).
Note that you can have up to 4 interfaces instead of 2.
Please let me know what version you are using then I can track this information.
Thanks.