I am confused. The ability to search for a starting value is already there.

Starting with the default value as provided for the option: mail.addr_book.autocompletequery.format = (or

 (DisplayName,c,@V)
 (FirstName,c,@V)
 (LastName,c,@V)
 (NickName,c,@V)
 (PrimaryEmail,c,@V)
 (SecondEmail,c,@V)
 (and
   (IsMailList,=,TRUE)
   (Notes,c,@V)
   )    
 )

I can puzzle out most of what this is doing, I think. I am guessing that the ",c," means "contains" because that is how it behaves: i.e The auto-complete drop-down includes entries where my search term exists anywhere in any of the named the fields. I can also guess that ',=,' means "is equal to": The entire named field must be the same as my search term (or a literal value as in the example). That I have confirmed by playing around with the option and watching how it behaves. So my question really is: Is this part of a bigger syntax? I just don't recognize it. If so, can I get hold of a description of the whole syntax somewhere?

Hello

looking at the Javascript code (AbAutoCompleteSearch.jsm) gives some insights, and they are not pretty. First of all, the default search is hardcoded in Javascript. As soon as you change something, the whole process is changed to call a c++ search done on the address book files (so it may be quite slower), and there are quite a few quirks - you can invalidate the email match all that you want, it will be ignored. Now the c++ syntax is in nsAbQueryStringToExpression.cpp:

 if (PL_strcasecmp(condition, "=") == 0)
   c = nsIAbBooleanConditionTypes::Is;
 else if (PL_strcasecmp(condition, "!=") == 0)
   c = nsIAbBooleanConditionTypes::IsNot;
 else if (PL_strcasecmp(condition, "lt") == 0)
   c = nsIAbBooleanConditionTypes::LessThan;
 else if (PL_strcasecmp(condition, "gt") == 0)
   c = nsIAbBooleanConditionTypes::GreaterThan;
 else if (PL_strcasecmp(condition, "bw") == 0)
   c = nsIAbBooleanConditionTypes::BeginsWith;
 else if (PL_strcasecmp(condition, "ew") == 0)
   c = nsIAbBooleanConditionTypes::EndsWith;
 else if (PL_strcasecmp(condition, "c") == 0)
   c = nsIAbBooleanConditionTypes::Contains;
 else if (PL_strcasecmp(condition, "!c") == 0)
   c = nsIAbBooleanConditionTypes::DoesNotContain;
 else if (PL_strcasecmp(condition, "~=") == 0)
   c = nsIAbBooleanConditionTypes::SoundsLike;
 else if (PL_strcasecmp(condition, "regex") == 0)
   c = nsIAbBooleanConditionTypes::RegExp;
 else if (PL_strcasecmp(condition, "ex") == 0)
   c = nsIAbBooleanConditionTypes::Exists;
 else if (PL_strcasecmp(condition, "!ex") == 0)
   c = nsIAbBooleanConditionTypes::DoesNotExist;

but do not have too high expectations, some things may not be implemented (soundslike is not)

Thank you, gp. This gives me some of what I need and provides pointers to the rest. Parsing little languages is never pretty. This fragment is at least clear about what it is doing. Geoff