Please refer to the Field Type information in the RDMLX Partition Settings in the Administrator Guide for details about enabling manual field creation in the partition. Also refer to the Field Definition option 1.2.14 Enable Field for RDMLX.
Note: If a field type is not enabled in a partition, the field type may still be used if loaded as an OTHER file. Developers are not allowed to manually create fields of the type that has been disallowed. Hence, you may see a field type (loaded from an other file) in the repository, but you may not be allowed to manually create that field type.
RDML and RDMLX Partition Concepts in the Administrator Guide.