Alright so I just bought an acoustic guitar (on the cheap side) and the strings felt really good so I asked the sales guy what size they were and he showed me a box of Martin's called 'Light' .012 to .054.

Then when I got the guitar home I notice it had a tag on it saying Aria strings (same as the guitar brand). I got on their website and assuming the strings are also 'Light', which what the saleguy was really trying to tell me, then they're .012 to .052.

So I notice there seems to be three main descriptions of string gauge - Medium, Light and Extra-Light. Is there any sort of broad agreement about what constitutes what category, if not among manufacturers, then amongst the playing community?
i think most people just name the string set by the smallest string, ie 12 gauge strings or 9 gauge for electric since it's the thinnest string and so on.
Schecter Diamond Series C-1 Elite
Roland Cube 30x
Blueridge BR-143
That's weird, or maybe there is another type. I usually use 11 gauge strings, which are normally marked "custom light". I find they work the best for me, though I would like to find some 12 gauge around here.
The terms "medium, light, custom light" and so on, in regards to strings, refers to the tension rating that the strings will have at concert pitch. A set of "lights" will have light(er) tension than a set of mediums.
Another confusing point to note is that there are "lights" available for both acoustic and electric, but they are NOT the same gauge. Standard lights for acoustic start at .012' while standard lights for electric will be .009'. Be sure to read the package closely when buying strings to insure you get the correct string for your particular application.