The Special Properties submenu of Text Properties can add or remove
three other useful text properties: read-only, invisible
and intangible. The intangible property disallows
moving point within the text, the invisible text property hides
text from display, and the read-only property disallows
alteration of the text.
Each of these special properties has a menu item to add it to the region. The last menu item, ‘Remove Special’, removes all of these special properties from the text in the region.
Currently, the invisible and intangible properties are
not saved in the text/enriched format. The read-only
property is saved, but it is not a standard part of the text/enriched
format, so other editors may not respect it.