Many aspects of Redet are configurable, primarily via the Configure menu.
Many programs have relevant options that are not set via the regular expression itself. Most of these are command-line flags or flags provided as function arguments (e.g. to the function that compiles regular expressions), but there are a few others. For example, individual string literals in Python may be tagged as either raw, which has the effect of preventing interpretation of escapes. Redet allows you to control this since it affects how regular expressions are interpreted.
Program-specific options are set via the Program Specific Features entry on the Configure menu. This menu lists the programs for which options may be set. Selecting a program pops up a control panel for that program.