Field help (VALDEF0) 

SEEINFO When a miscellaneous table is entered, it is possible to give a default value to each miscellaneous table.
This default value is not necessarily suggested.

The rule is that: this default value is suggested if the user is using a mandatory field of the miscellaneous table type.

If the field is not mandatory (except for particular cases), the default value of the miscellaneous table is not taken into account.