Callsign Searches
If you type in a pattern that the system recognizes as an amateur radio callsign, it will do a Callsign Search. Use * to match any characters and ? to match a single character. Examples: VE*ZD finds VE1ZD, VE1AZD, VE3CZD, etc. VA?ZEB finds VA1ZEB through VA9ZEB. *DX finds all callsigns ending in DX.

Advanced Searches
If you enter text that isn't recognized as a callsign, the system does an Advanced Search. It defaults to assuming that whatever you've typed in is intended to be a name search, and it searches all 1.7+ million names for any that match your search string. You can take it much further if you wish, though. Just remember, instead of using wildcards like in callsign searches, you use fields and operators.

You may use the following fields: certs, certification, certifications, province, prov, state, region, city, firstname, lastname, name, callsign, country, expired, club, clubname, clubcity, clubprov

You may use the following operators: equals, =, includes, excludes, startswith

The expired field is special: use expired=true or expired=false. This only affects US records (Canadian certifications don't expire). All Canadian records are always classed as expired=false.

The club field is also special: use club=true to find club stations or club=false for individuals. Use clubname, clubcity, or clubprov to search within club details. Club data is currently only available for Canadian callsigns.

You can combine as many of those as you want. For example, all of these are valid searches.

country equals CA lastname equals natarajan
firstname includes reg certs includes advanced
state=oregon firstname=erika
natarajan firstname excludes reg
expired=true region=pa
club=true clubname includes vancouver

Try any combination you can think of. The odds are good you'll find what you're looking for. Or just type in a name or callsign. That'll work, too.