Mailcrypt is an Emacs Lisp package which provides a simple but
powerful interface to cryptographic functions for mail and news.
With Mailcrypt, encryption becomes a seamlessly integrated part of your mail
and news handling environment. Mailcrypt can automatically fetch public keys
to encode, decode, and verify messages, and can be configured to automate
mailing through anonymous remailers.
Although Mailcrypt may be used to process data in arbitrary Emacs buffers, it
is most useful in conjunction with other Emacs packages for handling mail and
news. Mailcrypt has specialized support for Rmail, VM, MH-E, and Gnus.
SGML is a major mode for editing SGML documents.
It contains a simple SGML parser and can work with any DTD.
(The most popular nowadays are the HTML DTD's. PSGML can turn your
emacs into the one of most powerful HTML editors and will be
ultimately flexible as well, since you could upgrade your editor by
just installing new DTD's). Functions provided includes menus and
commands for inserting tags with only the contextually valid tags,
identification of structural errors, editing of attribute values in
a separate window with information about types and defaults, and
structure based editing.
SGML, a language for encoding the structure of a document, is an ISO
standard: ISO 8879:1986 'Information processing - Text and office
systems - Standard Generalized Markup Language (SGML)'.