The search function is like any search on a forum, one word or a series of numbers for an ecu can be used, but it's allso possible to look for a larger range of results.

Through the use of the * sign you can make larger search queries.
This is the reason why all files need to be in a certain logical naming format.

Try searching for example:

*1.9*115* If you are looking for a car with 1.9 engine and 115HP.

or

*golf*TDI* if you want to see all the golf tdi files.