XMLports

The possible values are Once and Zero (0). The default value is Once.

The maximum number of times an element can appear is determined by the value of the MaxOccurs Property. The MinOccurs and MaxOccurs properties conform to the standard occurrence constraints that are used when defining XML schemas.

In the Classic client, the minimum number is 0. In the RoleTailored client, if you use Lazy API for XML (LAX), then the minimum number is 1. If you do not use LAX, then the minimum number is 0.

The maximum number can be either 1 or infinite.

Reference