The Contents of IMBNOV90.ARC include:

--- Multiuser programming in BASIC

  FILELOCK BAS

--- Checking on credit cards

  CHKSUM   BAS

--- The further adventures of variable sharing
-- COMMON programs

  MODULE2  BAS
  TCOMMON  BAS
  TCOMMON  MAK

-- CHAINED programs

  TCHAINED BAS
  TSTART   BAS
  TCHAINED BI