Contact records having multiple categories

Can em Client allow me to identify a Contact record as belonging to several user-defined categories? Eg, Can I tag or check off my cousin as… a Relative, AND as a Business Customer, AND as someone who is in my Sailing Club, AND as someone who get certain kinds of photos or documents, AND as …? AND, then, can I SORT and FILTER contacts on any ONE or SEVERAL of these user-defined categories???

Yes, you can.
Filter is hidden in Advanced search - click on the little arrow in the search bar and choose Advanced search,

Are instructions for doing this (sorting, FILTERING, filtering on several values, etc.) also hidden in some mysterious place??? In other words, Does emClient have a comprehensive Instruction Manual for all the features of emClient, or must the user already know the right lingo & technical terms in order to to find the feature in a Help menu to get the instruction he or she needs?

I was able to find these instructions in a few seconds - type in the search box in Help file “filtering”.