Internal Error #999

  (#110250) It has to do with calling a function via a macro that was
  not linked in.  Look for a function that you are calling via a macro
  like:

  nVar   := "UDF()"
  RetVal := &nVar

  ... However, I was unable to reproduce this error using this example.

  (Mail) Forest Belt [70054,3664] received IE #999 when linking a Summer    ~
  '87 UDF into a home built .LIB file with a group of .ASM and 5.0 UDFs.

  I was able to verify this by writing a program that called a S87 compiled
  function.  Rtlink will warn you that you are attempting to link a S87
  module with a 5.0 one, and will show "_VSTD" and "SUMMER87" as undefined
  symbols.  Apparently, Clipper is attempting to call one of these functions
  when it dies with the IE #999.