This is a BPCS artifact in SSA programming which can present a nightmare for some maintenance programmers. Many BPCS programs are generated by AS/Set creating programming source code not intended to be read by a human being. As BPCS versions march into the future, more and more of the BPCS code is re-written using this approach.
According to the BPCS-L community, we are supposed to modify programs via AS/SET however, there are versions of BPCS marketed such that a company can "save money" by getting the source code but not the AS/SET then ask its staff to modify the source code that was generated this way. Some of that is manageable, but not that which very heavily uses soft coding.
In soft coding, instead of field names with variables whose function is obvious, at time of execution a substitution is made, based on the library list. The reason for this has to do with national languages. People who are native speakers English, French, Spanish, Chinese, etc. all look at the same data, through the filters of something in the library list to present the data in their language.