network mask for SNMP on AP9640? (resolved)

[cabricharme]

Hopefully a simple question... How do I open a specific network segment (aka subnet aka CIDR aka IP range) for SNMP access to an APC device with an NMC3 like AP9640?

What I tried (individual IP):

Configure SNMPv1 Access Control
Access Control
---------------------------------------------------
Community Name	NMS IP/Host Name	Access Type
--------------	----------------	-----------
YaddaBaddaVadda 10.11.12.200		Read

... which worked.... ✅ While anything below - doesn't despite supposedly opening a wider scope:

Community Name	NMS IP/Host Name	Access Type
--------------	----------------	-----------
YaddaBaddaVadda 10.11.12.0			Read
YaddaBaddaVadda 10.11.12.0/24		Read

Thanks!

P.S. Resolved! Per User's Guide (PDF, p.48), 10.11.12.255 opens the /24 subnet for the address.