Description

   The decc$feature_set function allows you to call the
   decc$feature_set_value function with a character-string feature
   name, rather than an index into an internal C RTL table.

   If successful, the function returns the previous value.

   On error, -1 is returned and errno is set to indicate the error.

   See also decc$feature_set_value, decc$feature_get, decc$feature_
   get_index, decc$feature_get_name, decc$feature_get_value.
   decc$feature_show, and decc$feature_show_all.