The Special Properties submenu of Text Properties has entries for
adding or removing four other text properties: read-only,
(which disallows alteration of the text), invisible (which
hides text), intangible (which disallows moving point within
the text), and charset (which is important for selecting a
proper font to display a character). The ‘Remove Special’ menu
item removes all of these special properties from the text in the
region.
The invisible and intangible properties are not saved.
Enriched mode also supports saving and restoring display
properties (see Display Property in the Emacs Lisp Reference
Manual), which affect how text is displayed on the screen, and also
allow displaying images and strings that come from sources other than
buffer text. The display properties also support execution of
arbitrary Lisp forms as part of processing the property for display,
thus providing a means to dynamically tailor the display to some
conditions that can only be known at display time. Since execution of
arbitrary Lisp opens Emacs to potential attacks, especially when the
source of enriched text is outside of Emacs or even outside of your
system (e.g., if it was received in an email message), such execution
is by default disabled in Enriched mode. You can enable it by
customizing the variable enriched-allow-eval-in-display-props
to a non-nil value.