The items following are the valid items. We will go through all of the options here, and explain what happens with most. A note about ID values. Each item must be a completely unique Number for in order for the Dialog table to be valid. If you think about it, it is inherently logical.
Title is fairly obvious.
This is what goes into the title bar of the dialog window. The size option sets the default size of the dialog box. The option option sets the default way the units you mention for positioning and sizing are to be interpreted. If using dbu, dialog boxes will look the same on everybody's screen, reguarless of settings. Read the versions.txt for more information.