Selecting Edit | Markings | Child Mode marks any children commands as long as the related parent command is also marked. A ‘child’ is a command that is dependent upon another command in order to function. For example, if you mark a feature that has a dimension, and you have this option selected, PC-DMIS will also mark the dimension for that feature.
If you don't select either the Parent Mode or Child Mode options, PC-DMIS marks only the selected items. If you unmark a marked parent command, the child command stays marked