Level 2 HTML Summary

A Level 2 HTML document can include the following elements and attributes in addition to Level 0 and Level 1 elements and entities. In this document, the elements are listed in all capital letters; the attributes are indicated by initial capital letters. In order to benefit from the information in this file, view both its HTML source as well as its rendered form in a Web browser. The tags are explained in the list below as well as demonstrated in this file.

HTML structure and comment elements

Level 2 specifies no additions in this category over Level 0's structure features.

The HEAD and Related Elements

Level 2 specifies no additions in this category over Level 1's head features.

The BODY and Related Elements

Form Elements

Forms are used to present an interface consisting of fill-in-the blank boxes, checklists, radio buttons, or other features to gather input from a user. The FORM element brackets an input data form; the elements INPUT, SELECT, OPTION, and TEXTAREA are used to set up areas within the Form for input.

A Form sets up a set of paired variable name fields and value value fields. The variable name is supplied in the Form. The user filling out the Form supplies or selects the variable values (except for variables with hidden values).

Each Form has a method and action associated with it. The method specifies how the data from the Form is to be handled in processing. The action identifies the executable program or script which will process the data from the From.

• FORM: delimits the start and end of a data input form. Forms can not be nested although there may be several in each document. Forms can include other elements such as lists or <PRE>.
  Attributes:
  • Action: This attribute specifies the URI of the program or script which accepts the contents of the form for processing. If this attribute is absent, the BASE URI of the Form is used.
  • Method: this attribute indicates the variation in the Froms-handling protocol which will be used in processing the Action program or script.
    • Query Forms that make no lasting changes in the state of hypertext or other data (for example, a database query) should use the Method "get." A Form using the get method is processed using the Action URI of the Form with a ? appended to it followed by the Form data appended in the application/x-www-form-urlencoded (as described below for the Enctype default format.)
    • Forms that do make a change in a database or hypertext or some other value should use the Method "post." The format of the message is application/x-www-form-urlencoded (as described below for the Enctype default format.)
  • Enctype: this identifies the media type (See RFC1590 also available via FTP from: ftp://ftp.merit.edu/documents/rfc/rfc1590.txt) that will be used for encoding the name/value pairs of
    the Form's data. This is needed for when the protocol identified in Method does not have its own format.

    The default encoding for all Forms is application/x-www-form-urlencoded and name/value pairs are represented as:

    • The name/value pairs are included in the data set in their order of appearance in the Form.
    • The name/value pairs are separated from each other by &.
    • The name fields are separated from the value fields by =.
    • All space characters in the variable names or values are replaced by +.
    • Non-alphanumeric characters are replaced by % followed by two hexadecimal digits representing the ASCII code of the character.
    • Line breaks are represented as control/line feed %0D0A.
• INPUT: This element is used for collecting information from the user.
  Attributes:
  • Align: this attribute is used only with the image Type (see list below). Possible values are "top," "middle," and "bottom," and define the relationship of the image to the text following it.
  • Checked: this attribute causes the initial state of a checkbox or radio button to be "selected." Without this attribute, the initial state is unselected.
  • Maxlength: this attribute sets a maximum number of characters that a user can enter in a text a field. The default value of this is unlimited.
  • Name: this is the symbolic name that is used in transferring and identifying the output from this element of the Form.
  • Size: specifies the field width as displayed to the user. If Size is less than Maxlength, the text field is scrollable.
  • Src: Used to define the source file for the image used with the attribute Type is set to "image."
  • Type:
    • checkbox: This is used for gathering data that can have multiple values at a time.
    • hidden: This is for values that are set by the form without input from the user.
    • image: An image field be used to submit the Form: when the user clicks on the image, the Form is submitted, and the x and y coordinates of the click location are transmitted with the name/value pairs.
    • password: This is a field in which the user enters text, but the text is not displayed (could appear as stars).
    • radio: Used to collect information where there is one and only one possible value from a set of alternatives. The Checked attribute can set the initial value of this element.
    • reset: This is used to reset and clear the Form to its default values. The Value attribute sets the string displayed to the user for this element.
    • submit: This button is used to submit the Form. The Value attribute sets the string displayed to the user for this element.
    • text: This is used for a single line of text; this uses the Size and Maxlength attributes. For multiple lines, use TEXTAREA (below).
  • Text: a single line text-entry area (Textarea element is used for multi-line text input). If the only element in the Form has attribute Text, then the user can submit the Form by hitting keyboard Enter (or Return).
  • Value: This sets the initial displayed value of the field or the value of the field when it is selected (the radio button type must have this attribute set).
• SELECT: this element allows a user to choose one of a set of alternatives. The OPTION element is used to define each alternative.
  Attributes:
  • Name: The logical name that will be submitted and associated with the data as a result of the user choosing select.
  • Multiple: By default, the user can only make one selection from the group in the SELECT element. By using the Multiple attribute, the user may select one or more of the OPTIONs.
  • Size: specifies the number of visible items. If this is more than one, the visual display will be a list.
• OPTION: This element occurs only within the SELECT element (above) and is used to represent each choice of the SELECT.
  Attributes:
  • Selected: indicates that this option is initially selected.
  • Value: If present, this is the value that will be returned by the SELECT if this option is chosen; otherwise, the value returned is that set by the OPTION element.
• TEXTAREA: This element is used to collect multiple lines of text from the user; the user is presented with a scrollable pane in which text can be written.
  Attributes:
  • Name: The logical name that will be associated with the returned text.
  • Rows: The number of rows that will be displayed (note the user can use more rows and scroll down to them).
  • Cols: The number of columns that will be displayed (the user can use the scrollbar to move through more columns if necessary.)

References

• HTML Level 2 specification ( http://www.w3.org/hypertext/WWW/MarkUp/html-spec/html-spec_2.html )
• Level 2 DTD ( http://www.halsoft.com/sgml/html-2.0/DTD-HOME.html ).

Copyright © 1995 by John December. All rights reserved.

Hyperlinks: Table of Contents