Symmetric List Processor 
A list processing system in which each list
cell contains both a forward and a backward link 
as well as a datum is described.  This system is intended
for imbeding in higher level languages capable 
of calling functions and subroutines coded in machine language.
 The presentation is in the form of FORTRAN 
programs depending on only a limited set of FORTRAN programs
depending on only a limited set of "primitive" 
machine language subroutines which are also defined.
 Finally, a set of field, particularly character, 
manipulation primitives are given to round out the system.
CACM September, 1963
Weizenbaum, J.
