Modifying Maxs render to texture UI

So I am trying to improve on Max 2014s Render to Texture UI. It seems a lot of the variables , names, values are set up like below

-- Output (Element) Properties Rollout
rollout selectedElementProps ~OUTPUT_CAPTION~ width:328 height:381
-- local functions

what is ~OUTPUT_CAPTION~ and where is that stored as things like this can not be changed it seems.