Gentlemen,

Thank you very much for the insightful discussion and suggestions.

I do fully agree with @jamie in his remark that regular expressions are 'twisted and mind boggling'. Indeed! But they have the big advantage of being pretty concise and once one is working, it can do a lot in less lines.

But I do understand that my problem is not amenable to treatment by a regex. I will try the code kindly provided by @jamie, and hope that it will be useful.

I noticed that both @jamie and @MarkML treated the problem as one of interpreting mathematical expressions, therefore considering more general solutions than what is really necessary. These numeric sequences are not expressions, they are *data*, and refer to measurements taken from several parts; so, for example, the sequence (200-)500-3500 represents the minimum (500) and the maximum (3500) values of a measurement, with (200-) representing an extreme lower value. Therefore, such sequences will ever be in that format (just with an occasional debris character like a starting comma). No character other than '-' will ever appear in them, and the value between parenthesis will only appear at the start (as an extreme lower value) or the end (as an extreme upper value) of a given sequence.

With **best** wishes,