A file is considered "read-only" if reading the file is allowed but writing to the file is not permitted.
What if the file has the following permissions (r and x)
root r-x file_name.xls
Is this file considered read only or not? Given that it has permissions to be executed
Yes, it is to be considered read only. Executing a file doesn't require write permission, only read permission, so there's no conflict in that combination of settings.