Security definition
Security definitions are set by specifiying them in the XML, one at a time inside of the root <securityrequest> element.
Note: All xml <element> names and attribute= names must be composed of lowercase
letters or numbers. Data values can be any case desired. Exceptions documented below.
Some of the parameters for a security definition are contained as attributes in the security definition XML element. Other parameters are contained inside the security definition in their own XML elements. If a parameter is required in order to uniquely identify a security definition, it is usually specified as an attribute, otherwise it is specified in the segment and field data.