Title of program: BCH may be improved by the alternative formulation of the theory on a body-centered hypercubic (BCH) lattice [2]. The method Catologue number: AABF for implementing the Monte Carlo algorithm for calculating Wilson loops and lines in an SU(2) gauge theory on a BCH Program available from: CPC Program Library, Queen's Uni-lattice is described. versity of Belfast, N. Ireland (see application form in this issue) Method of solution Computer: DEC VAX 11/750; Installation: Northeastern SU(2) gauge theory is simulated by importance-sampling Monte Univ., Dept. of Physics Carlo methods on a BCH lattice. The modified heat-bath method of Creutz [3] is used to thermalize the lattice. Operating system: DEC VAX 11/750: VMS 3.6 Restrictions on the complexity of the program Programming language used: VAX-il FORTRAN-IV plus (a) In order to correctly compute the Wilson lines, the lattice (FORTRAN-77 with VAX enhancements) must have an even length. (b) The main memory allocation in the program is for the 12 High-speed storage required: 128 Kwords (1000 pages; virtual arrays ALAT1 ALAT4, BLAT1 BLAT4, memory system allows less) CLAT1 CLAT4 each dimensioned to 12xISIZE 4 and 3 arrays MSHIFT, MBSHIFT and MCSHIFT dimensioned to Number of bits in a word: 32 24 x ISIZE4 where ISIZE is the lattice length. Since the VAX is a virtual memory machine the only real limitation on program Peripherals used: terminal, pnnter size is given by the available virtual memory. In practical terms, if the program far exceeds the physical memory (one megaword Number of lines in combined program and test deck: 944 . on the test machine) then most of the CPU time is spent doing disc I/O operations.