*** DEPRECATED FIELD - See Appendix 6-E: 5.Deprecated various FIX 4.3-introduced "Repo" Fields [deprecated in FIX 4.4] ***
Underlying security's RepoCollateralSecurityType.
See RepoCollateralSecurityType (239) field for description
(Note tag # was reserved in FIX 4.1, added in FIX 4.3)