In the past, hundreds of words such as Bank, Company, Trustee etc. were abbreviated as, BK, CO, TR etc,. This practice was initiated because of the limited length of space allocated in the electronic format and was potentially confusing. We are no longer constrained by the length of space.
From 1964 through 1990, the first word of an index entry was abbreviated so, for example, SECURITY PACIFIC NATIONAL BANK would appear as SEC PAC NATL BK.