The process-context module provides access to the context from which Scheme was invoked and to which it returns (to be less mealy-mouthed, the operating system). It exports the 4 identifiers environment-variable, environment-variables, command-line, quit. None of these are in IEEE Scheme or R5RS. The first two are in SRFI 98, the latter two in R6RS.
WG1 voted to accept this module.