# ifpresent

The keyword is only used in conjunction with template definition. It denotes one the matching mechanism where the listed values are only checked when the field is present. It can be applied to optional fields only.

Related keyword:

- template

### (value_list)ifpresent

- value_list is a comma separated list containing all the values that are permitted for the concerned field. It will only be checked when the field is present.

BNF definition of ifpresent