Technically, there is no such thing as a "URL" field in FileMaker. This would apparently be a field of type text or a calculation field with (hopefully) a text result type specified.
Performing a find on such a field should be just as searchable as any other text field, but layout design details might prevent you from doing so--as is the case for any text field.
Does "not allowing me to search" mean that you can't put the cursor into the field when in find mode?
Such would be the case for a field with global storage specified or if field access is not permitted when in Find Mode--an option that can be specified on the data tab of the inspector.
Correct, you cannot enter search criteria into a container field.
But a calculation field defined as GetAsText ( containerField ) will return the text that is part of the data stored in a container field. This would include the file name and would be searchable.
many thanks...that worked perfectly.