/sys$common/syshlp/helplib.hlb FORTRAN, Intrinsic Procedures, IBCLR  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  IBCLR (integer, position)

  A function that returns the value of the first argument with the
  specified bit set to 0.  The low-order bit is position 0.

  +------+---------+----------+------------+-------------+
  | Args | Generic | Specific |  Argument  | Result Type |
  +------+---------+----------+------------+-------------+
  |  2   |  IBCLR  | IIBCLR   | INTEGER*2  | INTEGER*2   |
  |      |         | JIBCLR   | INTEGER*4  | INTEGER*4   |
  +------+---------+----------+------------+-------------+