General Q: Why was it thought of to use Inverse subnet masks on ACL's?

[m.haran]

Just a general question really. Why was it thought of to use Inverse subnets when setting up ACL's. If anyone can answer it would be appreciated.

[hadbou]

As far as I know, there is nothing significant. The programers have made it that way and left it that way. Some programers used 1 as don't care bit and some used 0 as don't care bit.