The S-57 format has a concept of features being related to one another by way of the LNAM subfield of the FFPT (Feature to Feature Object Pointer) field. These relationships are encoded in the LNAM_REFS{} list attribute of FME features when such relationships exist.
In the S-57 format, these relationships are marked as being master, slave, or peer-to-peer. In practice, though, the only values that exist are master-to-slave pointers, so the explicit relationship is not preserved.
Each feature is also tagged with an LNAM value, which is the unique identifier for the feature within a single file.
FME can be used to associate the geometry of slave features with their master, as shown in this example mapping file fragment.
#==================================================================
# Collect geometries for C_AGGR objects.
FACTORY_DEF * TeeFactory \
FACTORY_NAME AggrGeomDuplicate \
INPUT FEATURE_TYPE * s57_type s57_point \
INPUT FEATURE_TYPE * s57_type s57_line \
INPUT FEATURE_TYPE * s57_type s57_polygon \
OUTPUT FEATURE_TYPE * \
OUTPUT FEATURE_TYPE GeomSource \
@KeepAttributes(LNAM,DSNM)
FACTORY_DEF * ReferenceFactory \
FACTORY_NAME AggrCollector \
INPUT REFERENCEE FEATURE_TYPE GeomSource \
INPUT REFERENCER FEATURE_TYPE C_AGGR \
REFERENCEE_FIELDS LNAM \
REFERENCER_FIELDS LNAM_REFS{} \
REFERENCE_INFO GEOMETRY \
GROUP_BY DSNM \
AGGREGATE_ONLY \
OUTPUT COMPLETE FEATURE_TYPE * \
OUTPUT INCOMPLETE FEATURE_TYPE *
Note: In Workbench, use the FeatureMerger transformer. This transformer takes input into two ports – Requestor and Supplier – and merges information from each Supplier onto the Requestor. For more information, open the FeatureMerger in Workbench and click the Help button.