That works like a dream - many thanks for such a quick response
If you need to use a multi-user solution, you will need to consider that once a record is flagged as part of a selection, you may want that selection to be unique to the user.
For this scenario, you will need to cretae a related table, which stores a reference to each record that a user selects. So when you click a button, that recordID will be set in a related record along with the user ID and something unique to indicate when the selected set refers to.
The chosen record can show in a portal, where you can give the user the ability to delete it if wrongly selected. A global field can be used in the relationship to ensure only the active users records are displayed.
Also, you can use a global field to calculate the amount of records that have been selected, so each user will have their own record count.
It would be simpler to make the flag field text formatted as a checkbox and make the link field a global with the text. Then you don't need any calculations.
Flag Field text is empty or "Flag"
List value = "Flag"
Field is formatted as a checkbox with the list assigned to it
The calcualated linking field value is "Flag"
The checking of the box toggles between flag and empty.
One can be used by you have to adjust the text on the checkbox so it doesn't show.
For multi-users add a global calulated field that uses get(accountname). Create a new in between table with two fields: account name and record id.
Link this new table to your current table with a double link: the account name to the global account name and the record id to the record id.
Drag your portal as shown elsewhere.
Your LINK button with
Set variable $_record_id the current record id
go to layout In between file
set field record id $_record_id
set field account name to get(accountname)
go to layout original layout
Each account now has its own set of records in this new table. You can count them before creating the new record, etc.
You could use just one link for the record id and filter the portal however...