On the Mac OS X platform, there is an open source resource editor utility called Rezilla. For those that are unfamiliar, a lot of the Rezilla utility’s functionality is similar to that of the ResEdit resource editor on the classic Mac OS platform.
When creating and editing resources with Rezilla, it appears that sometimes the resource’s data will include data that is supplied by Rezilla or generated by Rezilla as opposed to being inputted by the individual who is using Rezilla. Some examples where this may be happening are listed below. It is possible that there are other instances that are not mentioned in the list.
- For ‘dftb’ resources, there is a 2-byte version field at the start of the resource that is given the value of 0. In addition, each data item entry (entry type 1) in a ‘dftb’ resource starts with a 6-bit “Reserved (6 bits)” field that has the value 0. In an entry, the “Font number” field may have the default value of 0. It might be the case that the “Font number” field does not have any effect if the “Use font” setting for the data item entry is not turned on.
- For a ‘DITL’ (dialog item list) resource, according to a programming book, each item in the list has a 4-byte reserved field that precedes the 8-byte display rectangle data. It may be the case that this reserved value is all zeroes by default.
- For a ‘dlgx’ resource, there is a 2-byte version number that appears to be given the value of 0. After that, there is a 28-bit reserved field that appears to have the default value of 0.
- For a ‘DLOG’ resource, there is a 4-byte RefCon field. This field may be given the value of 0 by default.
- For a ‘MENU’ resource, according to a programming book, there is a 2-byte menu ID field and then there are two 2-byte placeholder fields that are intended to hold the menu width and menu height after the resource’s data has been loaded into memory. Perhaps these two placeholder fields are given a default value of 0 when a ‘MENU’ resource is created in Rezilla. Also, in a ‘MENU’ resource there is a 2-byte field for the menu definition resource ID and after that there is a 2-byte placeholder value. After the data for the menu’s items, there is a 1-byte placeholder field at the end of a ‘MENU’ resource. For each of the menu items in a ‘MENU’ resource, there are fields for optionally specifying an icon, a keyboard equivalent, a marking character, and a font style for the item. My guess is that the defaults for a menu item would be no icon, no key equivalent, no marking character, and a plain style.
When a ‘MENU’ resource is being edited in Rezilla’s ‘MENU’ resource editor, there are actions that will cause Rezilla to conveniently create a corresponding ‘xmnu’ resource for the menu. From what I can tell, the ‘xmnu’ resource that Rezilla creates for a ‘MENU’ resource has an entry for each menu item. If a menu item is a separator line, the ‘xmnu’ resource has a skip item (entry type 0); otherwise, the ‘xmnu’ resource has a data item (entry type 1.) For a data entry in an ‘xmnu’ resource, there may be certain defaults for the fields in the entry. For example, no command ID may be specified and the Reference constant 1 and Reference constant 2 fields each have the value 0.
- When entering text into a string in a ‘STR#’ resource, it is possible to add line breaks by pressing the Return key and it is also possible to paste in text from elsewhere that includes line breaks. When a ‘STR#’ resource is saved, it may be that Rezilla uses a carriage return character (ASCII code 13) in the resource data to indicate a line break. From what has been said elsewhere, the classic Mac OS platform (prior to Mac OS X) would use a carriage return (ASCII code 13) to indicate a line break and Unix platforms would use a linefeed character (ASCII code 10) to indicate a line break.
- When entering text into a ‘TEXT’ resource with the ‘TEXT’ resource editor in Rezilla, it is possible to add line breaks by pressing the Return key and it is also possible to paste in text from elsewhere that includes line breaks. When a ‘TEXT’ resource that was edited in the ‘TEXT’ resource editor is saved, it may be that Rezilla uses a carriage return character (ASCII code 13) in the resource data to indicate a linke break. From what has been said elsewhere, the classic Mac OS platform (prior to Mac OS X) would use a carriage return (ASCII code 13) to indicate a line break and Unix platforms would use a linefeed character (ASCII code 10) to indicate a line break.
The information in the Rezilla utility version 1.1 indicates that the Rezilla software is licensed under the GNU General Public License (GPL), version 2 or any later version. My understanding is that the license requires all copies of Rezilla to be licensed under the GPL version 2 or later and for all derivative works of the Rezilla software to be licensed under the GPL version 2 or later.
Given the previously mentioned details about resource types, there is the following question: If I use the Rezilla software to create a ‘dftb’ resource or a ‘DITL’ resource or a ‘DLOG’ resource or a ‘dlgx’ resource or a ‘MENU’ resource or a ‘STR#’ resource or a ‘TEXT’ resource or an ‘xmnu’ resource (or multiple instances of such resources), is the resource a derivative work of the Rezilla software (which would mean that the resource’s data would be subject to the GNU General Public License version 2 or later) or is it permissible for me to distribute the resource(s) to others under my own non-GPL licensing terms?
