Is the record that you are trying to isolate a record that is in the current found set of records produced by your script?
There are several possible methods that you can use that all produce similar (but not identical) results:
1) You can return to find mode and constrain the found set again specifying the value from the global field as criteria. This reduces your found set to just the matching records. While in Find Mode, set field can copy data from the global field into a specified field in order to set up the needed find criteria before constraining the found set.
See this thread for examples of using set field with global fields in that manner: Scripted Find Examples
2) A looping script can loop through the found set of records and stop on the first one that matches the specified value in the global field. This leaves your found set unchanged but now the specified record is the current record in that found set.
3) A relationship can be used with Go To Related records to either pull up a found set of just the specified record(s) or the same found set as your current script but with the record matching this global value selected as the current record.
Thankyou for your answer as the number of records is minimal I used a looping script as below;
Go to Record/Request/Page [First]
Exit Loop If [TableName::FieldName = TableName::GlobalFieldName]
Go to Record/Request/Page [Next; Exit after last]
This script works perfectly for what I needed I much appreciate the help.