HTML Allowed Nesting

Allowed nesting of elements in HTML 4 (and XHTML 1.0)

Nesting rules for HTML 4.01 Transitional

HTML

HEAD
- TITLE (required)
- SCRIPT, STYLE
  - CDATA
- ISINDEX, BASE, META, LINK (empty)
- OBJECT
BODY
- INS, DEL (special rules apply)
  - flow
- flow
  - block
    - P, H1, H2, H3, H4, H5, H6
      - inline
    - UL, OL
      - LI
        
        flow
    - DIR, MENU
      - LI
        inline exluding block
    - DL
      - DT
        
        inline
      - DD
        
        flow
    - PRE
      - inline excluding IMG, OBJECT, APPLET, BIG, SMALL, SUB, SUP, FONT, BASEFONT
    - DIV, CENTER, BLOCKQUOTE, IFRAME
      - flow
    - NOSCRIPT
      - flow
    - NOFRAMES
      - flow
    - FORM
      - flow excluding an enclosed FORM
    - ISINDEX, HR (empty)
    - TABLE
      - CAPTION
        
        inline
      - COLGROUP
        COL (empty)
      - COL (empty)
      - THEAD, TBODY, TBODY
        
        TR
        
        TH, TD
        
        flow
    - ADDRESS
      - inline
      - P
        
        inline
    - FIELDSET
      - #PCDATA
      - flow
      - LEGEND
        
        inline
  - inline
    - #PCDATA
    - TT, I, B, U, S, STRIKE, BIG, SMALL, FONT, EM, STRONG, DFN, CODE, SAMP, KBD, VAR, CITE, ABBR, ACRONYM, SUB, SUP, Q, SPAN, BDO
      - inline
    - A
      - inline excluding an enclosed A element
    - OBJECT, APPLET
      - PARAM (empty)
      - flow
    - IMG, BASEFONT, BR (empty)
    - SCRIPT
      - CDATA
    - MAP
      - AREA (empty)
      - block
    - INPUT (empty)
    - SELECT
      - OPTGROUP
        
        OPTION
      - OPTION
    - TEXTAREA
    - LABEL
      - LABEL excluding enclosed LABEL
    - BUTTON
      - flow excluding A, INPUT, SELECT, TEXTAREA, LABEL, BUTTON, FORM, ISINDEX, FIELDSET, IFRAME

Nesting rules for HTML 4.01 Frameset

HTML

HEAD
FRAMESET
- FRAMESET (note recursion)
- FRAME (empty)
- NOFRAMES
  - BODY

Allowed nesting of elements in HTML 4 Strict (and XHTML 1.0 Strict)

HTML

HEAD
- TITLE (required)
- SCRIPT, STYLE
  - CDATA
- BASE, META, LINK (empty)
- OBJECT
BODY
- INS, DEL (special rules apply)
  - flow
    - block
    - inline
- SCRIPT
  - CDATA
- block
  - P, H1, H2, H3, H4, H5, H6
    - inline
      - #PCDATA
      - TT, I, B, BIG, SMALL, EM, STRONG, DFN, CODE, SAMP, KBD, VAR, CITE, ABBR, ACRONYM, SUB, SUP, Q, SPAN, BDO
        
        inline
      - A
        
        inline excluding an enclosed A element
      - OBJECT
        
        PARAM (empty)
        flow
      - IMG, BR (empty)
      - SCRIPT
        
        CDATA
      - MAP
        
        AREA (empty)
        block
      - INPUT (empty)
      - SELECT
        
        OPTGROUP
        
        OPTION
        
        OPTION
      - TEXTAREA
      - LABEL
        LABEL excluding enclosed LABEL
      - BUTTON
        flow excluding A, INPUT, SELECT, TEXTAREA, LABEL, BUTTON, FORM, FIELDSET
  - UL, OL
    - LI
      - flow
  - DL
    - DT
      - inline
    - DD
      - flow
  - PRE
    - inline excluding IMG, OBJECT, BIG, SMALL, SUB, SUP
  - DIV
    - flow
  - BLOCKQUOTE
    - block
    - SCRIPT
      - CDATA
  - NOSCRIPT
    - flow
  - FORM
    - block excluding an enclosed FORM
    - SCRIPT
      - CDATA
  - HR (empty)
  - TABLE
    - CAPTION
      - inline
    - COLGROUP
      - COL (empty)
    - COL (empty)
    - THEAD, TBODY, TBODY
      - TR
        
        TH, TD
        
        flow
  - ADDRESS
    - inline
  - FIELDSET
    - #PCDATA
    - inline
    - flow
    - LEGEND
      - inline