Toward shared variable events implications of DSVE in APL2

APL2 has two extensions for shared variables, a system function, DSVS, which returns the access state of variables and a system variable, USVE, which provides a rudimentary mechanism for detecting events associated with shared variables. Implementation of these constructs raises questions about the signalling rules followed by Shared Variable Processors. This paper discusses those questions and suggests that further research be done.