1. Serial Line Internet Protocol. 2. SYmmetric LIst Processsor. EarlY 1960' s list processing subroutine package for Fortran bY J. Weizenbaum. Later also embedded in MAD and ALGOL. ["SYmmetric List Processor", J. Weizenbaum CACM 6:524-544(1963). Sammet 1969, p.387].