Karen, adding to what Gregory already explained and suggested, another possibility would be "(\[\d+)[^\d]+(\d+\])", meaning that the separator could be anything non-digit that could extend beyond a single character. For instance, it would match and replace "1st-title: ANAME-HER : 3520931 place[99 - 100]" into "1st-title: ANAME-HER : 3520931 place[99.100]".

>actually your solution greg does well but does not replace a space with a dot whereas Antonio's solution does.
>
>s ='1st-title: ANAME-HER : 3520931 place[4443 4444]' &&&XXX
>
>using Antonio's middle parameter replaces space with dot - so perhaps combining the two.
>

>regexObj.Pattern = '(\[\d{1,4}).(\d{1,4}\])'
>