Input plugin operations

This page applies to Harlequin v13.1r0 and later; and to Harlequin MultiRIP but not Harlequin Core

Input plugins need to respond to selector calls making inquiries about supported channel classes, dialogs and parameter types; requests for file operations, such as initializing a new channel, opening and closing connections on a channel, setting parameter values, and so on.

Sometimes these operations are necessary after executing a PostScript language operator (for example, using the file operator where the filename indicates a channel) and other times the need is because of something done implicitly - for example when the PostScript language scanner requires more data.