Sadly, we still cannot search for some of the most common text strings like "F4M" or "P47" because they are deemed to be too short or too common. And "F-4M", "F.4M" and "P-47D" are also illegal because of the use of punctuation. And when I have tried enclosing the search string in quotation marks, I have had inconsistent results . . .
So, as Larry says, more use of 'tags' is the way we should be going, especially if these are used consistently . . .