The full MXP definition can be found at: https://www.zuggsoft.com/zmud/mxp.htm

Base MXP Elements:

<!ELEMENT> <!EL>
<!ELEMENT element-name [definition] [ATT=attribute-list] [TAG=tag] [FLAG=flags] [OPEN] [DELETE] [EMPTY]>
Desc: Define a new element.
Ex:<!ELEMENT boldtext '<COLOR &col;><B>' ATT='col=red'>

<!ATTLIST> <!AT>
<!ATTLIST element-name attribute-list>
Desc: Add attributes to an element.
Ex: <!ELEMENT Sound EMPTY>
<!ATTLIST Sound FName V=100 L=1 P=50 T U>

<!ENTITY> <!EN>
<!ENTITY Name Value [DESC=description] [PRIVATE] [PUBLISH] [DELETE] [ADD] [REMOVE]>
Desc: Define an entity &entityname;
Ex: <!ENTITY Start "<em>">
<!ENTITY End "</em>">
&Start;This text is emphasized&End;

<VAR> <V>
<VAR Name [DESC=description] [PRIVATE] [PUBLISH] [DELETE] [ADD] [REMOVE]>Value</VAR>
Desc: Define an entity &Name;, but the value is between the open and close tags.
Ex: <VAR Hp>100</Var>

<!TAG Index(20-99) [WINDOWNAME=string] [FORE=color] [BACK=color] [GAG] [ENABLE] [DISABLE]>
Desc: Define an tag index, which is invoked with ANSI <ESC> codes.
Ex: <!ELEMENT Auction TAG=20><!TAG 20 Fore=red>
<ESC>[20zA nice shiny sword is being auctioned.
<Auction>Also, a gold ring is being auctioned.</Auction>
<!TAG 20 Fore=LIGHTBLUE><ESC>[20zA nice shiny sword is being auctioned.
<Auction>Also, a gold ring is being auctioned.</Auction>

<B> <BOLD> <STRONG>
<I> <ITALIC> <EM>
<U> <UNDERLINE>
<S> <STRIKEOUT>
<C> <COLOR FORE=foreground [BACK=background]>
<H> <HIGH>
<NOBR>
<P>
<BR>
<SBR>
&nbsp;
<H1>, <H2>, <H3>, <H4>, <H5>
<H6>, <HR>, <SMALL>, <TT>
<A href=URL [hint=text] [expire=name]>
Desc: Various common HTML tags.

<SEND [href=command] [hint=text] [prompt] [expire=name]>
<SEND> menus (see example)
<EXPIRE [Name]>
Desc: Generate a link that sends a mud command, or creates a menu of such commands.
Ex: <send href="buy bread">bread</send>
<SEND "command1|command2|command3" hint="click to see menu|Item 1|Item 2|Item 2">this is a menu link</SEND>

<GAUGE EntityName [Max=EntityName] [Caption=text] [Color=color]>
Desc: Create a progress gauge bar.

<STAT EntityName [Max=EntityName] [Caption=text]>
Desc: Create a status entry ie Entity/MaxEntity

<FRAME NAME ACTION=OPEN|CLOSE|REDIRECT|MODIFY [TITLE=title] [SCROLLING=yes|no|x|y] INTERNAL|FLOATING|[FLOATING=CLOSE] [DOCK=name] [ALIGN=LEFT|RIGHT|BOTTOM|TOP] [LEFT=N%|Npx] [TOP=N%|Npx] [WIDTH=N%|Npx] [HEIGHT=N%|Npx] [IMAGE=url] [IMGOP=opacity%]
Desc: Creates a new frame inside the current one.
Ex: <FRAME MYFRAME ACTION=OPEN INTERNAL ALIGN=TOP HEIGHT=20% SCROLLING=no>

<DEST NAME=frame X=unsupported Y=unsupported EOF>
Desc: Changes the FRAME destination of text inside the DEST tags. Use EOF to clear the frame before new content.
Ex: <DEST MYFRAME>

<RELOCATE [URL=host] [PORT=port] [QUIET]>
Desc: Cause a new mud connection to be made.

<USER>
<PASSWORD>
Desc: Causes the client to send the username and password. Use with RELOCATE.

<IMAGE [FNAME=NAME] [URL=url] [T=type] [H=height] [W=width] [HSPACE=h padding] [VSPACE=v padding] [ALIGN=left|right|top|middle|bottom] [ISMAP]>
Desc: Display an image

<SOUND [FNAME=name] [V=volume 0-100] [L=repeats] [P=priority 0-50] [U=url]> <MUSIC [FNAME=name] [V=volume 0-100] [L=repeats] [P=priority 0-50] [U=url]>
Desc: Play a sound.

Special MXP Elements:

<INPUT [NAME=name] [TYPE=type] [VALUE=value]>
Generates the standard input html tag of the given type and default value. ONCHANGE events will set the entity/variable [name] equal to its current value, while also dispatching an event of the given [name], so try to keep it unique!