The Hierarchy of the HTML 2.0 DTD

A Little Bit of SGML contains a walkthrough of the HTML tree, describing the SGML syntax used to define content models. If you have not attempted to read a DTD previously, I strongly recommend you look at this first.

For simplicity, the content models in the trees below assume HTML.Recommended, HTML.Highlighting and HTML.Forms are all included. However, deprecated elements appear in the trees themselves. For a full description of the syntax of HTML 2.0 elements, see the HTML 2.0 Specification, now published as RFC 1866.

[HTML tree] [HEAD tree] [BODY Outline tree] [%text tree] [%block tree] [Full BODY Tree]

The HTML Tree

<!ELEMENT HTML O O (%html.content)>

% html.content "HEAD, BODY"
- HEAD (%head.content) +(META|LINK)
  - % head.content "TITLE & ISINDEX? & BASE? %head.extra"
  - META EMPTY
  - LINK EMPTY
- BODY %body.content
  - %body.content (%heading|%block|HR|ADDRESS|IMG)*
- PLAINTEXT - Deprecated %literal

The HEAD Tree

<!ELEMENT HEAD O O (%head.content) +(META|LINK)>

% head.content "TITLE & ISINDEX? & BASE? %head.extra"
- TITLE (#PCDATA)* -(META|LINK)
- ISINDEX EMPTY
- BASE EMPTY
- % head.extra ""
  - ""
  - "& NEXTID?" - not Recommended EMPTY
META EMPTY
LINK EMPTY

The BODY Tree

The first list is an abbreviated tree, and so doesn't include the intricacies of %text and %block. A full BODY tree can be found at the end.

BODY Outline Tree

<!ELEMENT BODY O O %body.content>

%body.content (%heading|%block|HR|ADDRESS|IMG)*
- %heading "H1|H2|H3|H4|H4|H6" (%text)*
  - %text "#PCDATA | A | IMG | BR | %phrase | %font"
- %text - not Recommended
- %block "P | %list | DL | %preformatted | %block.forms"
  - P (%text)*
  - %list " UL | OL | DIR | MENU "
  - DL (DT | DD)+
  - %preformatted "PRE"
  - %block.forms "BLOCKQUOTE | FORM | ISINDEX"
- HR EMPTY
- ADDRESS (%text|P)*
- IMG - Recommended EMPTY

The %text Tree

%text "#PCDATA | A | IMG | BR | %phrase | %font"
- #PCDATA
- A %A.content -(A)
  - %A.content "(%text)*"
    - %heading - not Recommended
    - %text
- IMG EMPTY
- BR EMPTY
- %phrase "EM | STRONG | CODE | SAMP | KBD | VAR | CITE " (%text)*
- %font " TT | B | I " (%text)*

The %block Tree

%block "P | %list | DL | %preformatted | %block.forms"
- P (%text)*
- %list " UL | OL | DIR | MENU "
  - UL | OL (LI)+
    - LI %flow
      - %flow "(%text|%block)*"
  - DIR | MENU (LI)+ -(%block)
    - LI %flow
- DL (DT | DD)+
  - DT (%text)*
  - DD %flow
- %preformatted "PRE"
  - PRE (%pre.content)*
    - %pre.content "#PCDATA | A | HR | BR"
      - #PCDATA
      - A
      - HR EMPTY
      - BR EMPTY
  - XMP|LISTING - Deprecated %literal
- %block.forms "BLOCKQUOTE | FORM | ISINDEX"
  - BLOCKQUOTE %body.content
  - FORM %body.content -(FORM) +(INPUT|SELECT|TEXTAREA)
    - %body.content
    - INPUT EMPTY
    - SELECT (OPTION+) -(INPUT|SELECT|TEXTAREA)
      - OPTION (#PCDATA)*
    - TEXTAREA (#PCDATA)* -(INPUT|SELECT|TEXTAREA)
  - ISINDEX EMPTY

The Full HTML 2.0 BODY Tree

Won't it be nice when your browser can expand and collapse nested lists for you?

%body.content (%heading|%block|HR|ADDRESS|IMG)*
- %heading "H1|H2|H3|H4|H4|H6" (%text)*
  - %text "#PCDATA | A | IMG | BR | %phrase | %font"
    - #PCDATA
    - A %A.content -(A)
      - %A.content "(%text)*"
        
        %heading - not Recommended
        %text
    - IMG EMPTY
    - BR EMPTY
    - %phrase "EM | STRONG | CODE | SAMP | KBD | VAR | CITE "
    - %font " TT | B | I "
      - (%font;|%phrase) - - (%text)*
- %text - not Recommended
- %block "P | %list | DL | %preformatted | %block.forms"
  - P (%text)*
  - %list " UL | OL | DIR | MENU "
    - UL | OL (LI)+
      - LI %flow
        
        %flow "(%text|%block)*"
    - DIR | MENU (LI)+ -(%block)
      - LI %flow
  - DL (DT | DD)+
    - DT (%text)*
    - DD %flow
  - %preformatted "PRE"
    - PRE (%pre.content)*
      - %pre.content "#PCDATA | A | HR | BR"
        
        #PCDATA
        A
        HR EMPTY
        BR EMPTY
    - XMP|LISTING - Deprecated %literal
  - %block.forms "BLOCKQUOTE | FORM | ISINDEX"
    - BLOCKQUOTE %body.content
    - FORM %body.content -(FORM) +(INPUT|SELECT|TEXTAREA)
      - %body.content
      - INPUT EMPTY
      - SELECT (OPTION+) -(INPUT|SELECT|TEXTAREA)
        
        OPTION (#PCDATA)*
      - TEXTAREA (#PCDATA)* -(INPUT|SELECT|TEXTAREA)
    - ISINDEX EMPTY
- HR EMPTY
- ADDRESS (%text|P)*
- IMG - Recommended EMPTY

[Top of page] [My copy of the HTML 2.0 DTD] [Introduction] [A Little Bit of SGML] [HTML 3.0 DTD Trees] [HTML 3.2 DTD Trees] [AWPA Useful Box] [Di's home page]

Last updated: 11 June 1996 by dkgsoft@ozemail.com.au (Dianne Gorman)

<URL:http://www.ozemail.com.au/~dkgsoft/html/html2.html>