A complete guide of available functions in business processes

Hi there,

I was very surprised to discover that when I (or my customer success manager) need a function for my business process (substring, for example) I need to go to stackoverflow or similar websites for this information.

I believe it should have been provided by BPM'online as a clear, well structured guide that contain all the available functions. The current guide is ridiculously unhelpful. 

Please provide your customer essential information, I shouldn't look for this information in other places.

Thank you,

Oren