25/18 is SLAG I think. I am big on having an in-between measure as the concept of loose and tight meeting at a point just seems ridiculous to me.

I have been making my own Poker Tracker rules (mainly influenced by playing £25NL) and they're based on the following concepts:

Pre-flop (VP$IP):
Tight - <18%
Semi-loose - 18-28%
Loose - > 28%

Pre-flop (pre-flop raise)
Aggessive: >7%
Neutral: 4-7%
Passive: <4%

Post-flop (aggression factor):
Aggressive: >1.7
Neutral: 1-1.7
Passive: <1