When one is not interested in the content of a particular field, one can employ a FillerField. This acts as a placehold that reserves space for the field, but the field is inaccessible. For example:
"Define the fields of the Win32 LOGPEN Structure"
defineField: #style type: DWORDField new;
defineField: #width type: SDWORDField new;
defineField: #unusedWidthY type: (FillerField byteSize: 4);
defineField: #lopnColor type: SDWORDField new
FillerFields can also be used for one off Structure Packing.
An alternative to filler fields, which is preferable when another suitable field type is available, is to send the #beFiller message to an ExternalField instance of the correct type; such fields will also be inaccessible.