One of the frustrating things about learning Houdini is the amount of expressions used to get things done. This is par for the course I know but today I was trying to figure out what exactly a $CR variable is, I'm happy to RTFM but I spent an hour just trying to find it in the manual. I do a search $CR, no dice. I know it's some sort of color variable so I search for that. nothing comes up. I find global VOP variables.. nothing there.

How would one find any info on this stuff? the manual is ridiculously hard to use in my opinion.

in plain simple way to understand $CR is red $ CB is Blue $CG is green or you could see as x,y,z or 1,2,3
Anyway I would recommend to move away as much as you can from local variables(still some local variables are useful), meaning all the $CR, $PT, $NUMPT etc
And get more familiar with Attributes @ much better in my opinion. So $CR will be @Cd.r or @Cd.x
If you want to know more about @

http://www.sidefx.com/docs/houdini15.5/vex/snippets [sidefx.com]

If you still want to know about Local variables I couldn't find the same thing for 15.5 but this still applies

http://www.sidefx.com/docs/houdini14.0/expressions/_globals [sidefx.com]

Sepu to the rescue again! Thanks!

I found that _globals page as well online but there's nothing in there about $CR so thanks for the explanation and the advice. I can see that they're really pushing these VEX expressions now but it wasn't clear to me until now what they were. Noticed them when I laid down a point SOP. I guess I can excuse myself from learning local variables if VEX is better.

Thanks!

I agree that these $ variables make learning Houdini harder than it should be. I come from a programming background so I kind of expected a location that lists them all like most programming languages have but it doesn't look like there is. What's also confusing is that there are the @ expressions which is not clear what the difference between the two are and why some of the $ ones don't have a @ equivalent ($F vs $FF).

local variables are being phased out, and they are local for a reason since not every node supports them
but if you have node that supports them it's usually stated in help

like for example above mentioned Group SOP
http://sidefx.com/docs/houdini15.5/nodes/sop/group#locals [sidefx.com]
which then points you to
http://sidefx.com/docs/houdini15.5/nodes/sop/standardvariables [sidefx.com]
as it probably supports them all

or Transform SOP
http://sidefx.com/docs/houdini15.5/nodes/sop/xform#locals [sidefx.com]
which has just subset mentioned

or Sweep SOP with it's own unique set of local variables
http://sidefx.com/docs/houdini15.5/nodes/sop/sweep#locals [sidefx.com]