the useage of Pt_CB_...?

I’m a new user of QNX,I shoule develop a app under PhAB.I read some book about it.the Pt_ARG_… could be used in function such as PtSetResource().Thanks for everyone who tell me the useage of Pt_CB_…
Some example code will be more helpfull.

for examples see HELP for PtAddCallback(…)

thanks qnxloader very much.