
Edit properties of a custom element
Custom elements don't have many settings. They refer to a script of type "data type" that can be edited in the script editor. The referenced script implements both parsing of some data in a file as well as translating changes back to the file.
Optionally you can specify an expression to compute the length of a custom element. This length will be passed to the parsing script method if it is smaller than the remaining space in the file.