[FX.php List] referencing a portal row

[Vision Computer Consulting]

The documentation reads

The SetPortalRow() function is used to edit a portal row, or to  
create a record via a portal row. It's
the equivalent of making several AddDBParam() calls using the full  
FileMaker portal syntax for the
field name: "relationship_name::fieldName.<recID>".

is <recID> the recordID of the Anchor record that contains the portal  
or a reference to the portal row number?