\ProvidesFile{iso-alphabetic.dbx}
  [2022/03/20 v0.4.1 ISO 690 biblatex data model extension]

\RequireBiber[3]

% Declare new fields
\DeclareDatamodelFields[type=list, datatype=name]{supervisor}
\DeclareDatamodelFields[type=field, datatype=literal]{dateaddon}

% Declare new fields for (specific / all) entry types
\DeclareDatamodelEntryfields[thesis]{supervisor}
\DeclareDatamodelEntryfields{dateaddon}