I have it showing up in a set of sample data when I try to work with a datasource using BK0001.  RVSpy shows:

         [4fb0.7ff.43dc] BK0001: BKACCT   [07:39:17.15].Read(view=0x10C6D314)
            [4fb0.7ff.43dc] BK0021: BKTNUM   [07:39:17.15].Put(view=0x10C6755C, field=1, size=8, verify=0, buffer='\46\43\42\41\4e\4b\20\20' -> 'FCBANK  ')
            [4fb0.7ff.43dc] 0 <==[07:39:17.17;t=0;ovh=0] {}
            [4fb0.7ff.43dc] BK0002: BKCUR    [07:39:17.17].Cancel(view=0x10C82AA4)
            [4fb0.7ff.43dc] 0 <==[07:39:17.17;t=0;ovh=0] {}
            [4fb0.524145.43dc] YC2124: ???????? [07:39:17.17].Cancel(view=0x2020204E)

There's nothing in programs, bk.ini or in csapp in the company or system databases. 

However - this only occurs in my macro when I call:

    dsBank.Fields("BANK").PutWithoutVerification fecBankCode.Value
    If dsBank.Read = False Then

The only thing that I can think of is that the system database is shared with a company database using Orchid's Extender product. But that application is VI, not YC.