As used in this subchapter, unless the context otherwise requires, “trust funds” means all assets and holdings of the various firemen's and policemen's pension funds of this state. In addition, other assets and holdings which are of a trust nature and are under the administration of political subdivisions of this state are, for purposes of this subchapter, to be considered trust funds. However, trust funds shall not include funds required to be maintained by ordinances, resolutions, or indentures securing bond issues of political subdivisions.