Definition lists

Definition lists allow you to identify a list of words or phrases and their corresponding definitions. A simple definition list formats as a two-column list: the terms you define appear in the left column, and the definitions for the terms appear in the right column. Definition lists are slightly more complex than the previous lists we've discussed, because of the additional tags required to construct them.

The tags used to create a definition list are:

DL: Begins a definition list. The required end tag ends the list.
DT: Identifies the term being defined. The definition term is formatted in the left column of the list. It does not require an end tag.
DD: Identifies the term description. Each definition description is formatted in the right column of the list, immediately opposite or below its associated term. It does not require an end tag.

You can also create headings for definition list columns. There are two additional tags that you can use to do this. They are:

DTHD: Defines a header for the definition term column.
DDHD: Defines a header for the definition description column.

Both of these tags are optional for creating definition lists. We'll show you how you can use them to enhance definition lists later on in this topic.

Here is an example of a definition list:

Figure 1. Definition list

             Department Codes

 Use the following codes for each of the
 matching departments:

 AP        Appliances

 AU        Automotive

 GA        Garden shop

 HB        Health and beauty

 HO        Home decor

 SP        Sporting goods

Here is the markup:

<!doctype dm system>
<panel name=deptcode width=42>Department Codes
  <area>
    <info width=40>
      <p>Use the following codes for each of the
      matching departments:
      <dl>
        <dt>AP
        <dd>Appliances
        <dt>AU
        <dd>Automotive
        <dt>GA
        <dd>Garden shop
        <dt>HB
        <dd>Health and beauty
        <dt>HO
        <dd>Home decor
        <dt>SP
        <dd>Sporting goods
      </dl>
    </info>
  </area>
</panel>

A definition list can contain multiple definition terms. The TSIZE attribute of the enclosing DL tag specifies the number of DT tags in a group and their respective widths. For example, TSIZE='10 5' specifies 2 definition term columns with sizes of 10 and 5 characters, respectively.

The DL tag has optional attributes:

TSIZE: specifies the space allocated for the term column or columns
BREAK: indicates if the definition formats on the same line as its associated term
COMPACT: determines if there is a space between each set of terms and descriptions
NOSKIP: suppresses the blank line normally placed before the list
INDENT: controls the indentation from the current left margin
FORMAT: controls the location of the definition term within the TSIZE space
DIVEND: determines whether a divider character is inserted following the DDHD and DD tag text
SPLIT: controls the format of the last DT tag in a multiple DT tag group

Use the TSIZE attribute to specify how much space you want for the definition term column (or columns). The default value is 10 bytes, which also sets the default number of DT tags to one. If you want to specify more (or less) space than the default, or multiple DT tags, use the TSIZE attribute to assign the value you want.

Use the BREAK attribute to specify where the definition descriptions are supposed to start (on the same line as the definition terms or on the next line). The BREAK attribute can be specified as NONE, ALL, or FIT.

NONE: The definition descriptions start on the same lines as the definition terms.
ALL: All of the definition descriptions start on the line after the definition terms.
FIT: The definition descriptions are to start on the next line only when the definition term does not fit in the allocated space and spills over into the description area.

The definition list in Figure 1 used the default BREAK=NONE. We'll define another list that uses BREAK=ALL.

<!doctype dm system>
<panel name=reverb1 width=52>Reverberations
  <area>
    <info width=50>
      <p>Reverberations is one of the most popular brands of electronic
      components available today.
      We stock the following Reverberations components:
      <dl break=all>
        <dt>CD Player Unit
        <dd>With auto-search, auto-off, power door, and
        a two-year warranty.
        <dt>Receiver
        <dd>Digital, 6-speaker hookup, and built-in
equalizer.
        <dt>Tape deck
        <dd>Supports metal and chrome cassettes, and comes with
        a two-year warranty.
      </dl>
    </info>
  </area>
</panel>

Figure 2 shows how this definition list formats.

Figure 2. Definition list (BREAK=ALL)

                   Reverberations

 Reverberations is one of the most popular brands
 of electronic components available today. We
 stock the following Reverberations components:

 CD Player Unit
           With auto-search, auto-off, power door,
           and a two-year warranty.

 Receiver
           Digital, 6-speaker hookup, and built-in
           equalizer.

 Tape deck
           Supports metal and chrome cassettes, and
           comes with a two-year warranty.

Because the TSIZE and BREAK attributes lend versatility to definition lists, we can rearrange this list practically any way we want. We'll change the BREAK value to FIT, and increase the TSIZE to 13 to show you what we mean. We'll also add headings to the list to show you how they format.

<!doctype dm system>
<panel name=reverb2 width=52>Reverberations
  <area>
    <info width=50>
      <p>Reverberations is one of the most popular brands of electronic
      components available today.
      We stock the following Reverberations components:
      <dl tsize=13 break=fit>
        <dthd>Component
        <ddhd>Features
        <dt>CD Player Unit
        <dd>With auto-search, auto-off, power door, and
        a two-year warranty.
        <dt>Receiver
        <dd>Digital, 6-speaker hookup, and built-in equalizer.
        <dt>Tape deck
        <dd>Supports metal and chrome cassettes, and comes with
        a two-year warranty.
      </dl>
    </info>
  </area>
</panel>

Here is how the panel looks now:

Figure 3. Definition list (BREAK=FIT)

                   Reverberations

 Reverberations is one of the most popular brands
 of electronic components available today. We
 stock the following Reverberations components:

 Component    Feature

 CD Player Unit
              With auto-search, auto-off, power
              door, and a two-year warranty.

 Receiver     Digital, 6-speaker hookup, and
              built-in equalizer.

 Tape deck    Supports metal and chrome cassettes,
              and comes with a two-year warranty.