XS_DIMENSION_DIGIT_GROUPING_COUNT
Category in Advanced options dialog: Dimensioning - general
Use this advanced option to specify the number of digits after which a space (default) or a separator character will be inserted in dimension values. If you set this advanced option to 3 (default), 154321 becomes 154 321.
This advanced option is model specific and the setting is saved in the options database. Reopen the model to activate the new value.