Some HTML functions that are rarely used but are not bad

1. group the content in the drop-down list
Optgroup is used as the <option> group in <SELECT>, but only IE6 is supported, as shown in the following example:
Your favorite team
BarcelonaReal MadridValenciaLaconiaChelseaArsenalManchester UnitedLiverpoolAC MilanMilanJuventusRome

< Select >
< Optgroup Label = "Spain" >
< Option > Barcelona </ Option >
< Option > Real Madrid </ Option >
< Option > Valencia </ Option >
< Option > Laconia </ Option >
</ Optgroup >
< Optgroup Label = "England" >
< Option > Chelsea </ Option >
< Option > Arsenal </ Option >
< Option > Manchester United </ Option >
< Option > Liverpool </ Option >
</ Optgroup >
< Optgroup Label = "Italy" >
< Option > AC Milan </ Option >
< Option > Milan </ Option >
< Option > Juventus </ Option >
< Option > Rome </ Option >
</ Optgroup >
</ Select >

2. Use <Ruby> and <RT> to add comments to text

We useVisual Studio. NET 2003Development tools provided by MicrosoftProceedProgramDevelopment
< Span Style = "Font-family: Arial; font-size: 12pt ;" > We use
< Ruby > < U > Visual Studio. NET 2003 </ U > < RT > < Span Style = "Font-family: Arial; font-size: 8pt; color: red ;" >
Development tools provided by Microsoft </ Span > </ Ruby > Program Development </ Span >

3. Use your own defined elements
Step 1 declare the namespace and use the xmlns tag attribute of the HTML Element
Step 2: Define custom tags in @ media Packaging
Step 3 use custom tags < Html Xmlns: mytag >
< Head >
< Style >
@ Media all {} {
Mytag \:T1 {color: red;Font-size:12pt}
Mytag \: t2 {} {Color:Green;Font-size:14pt}
Mytag \: T3 {} {Color:Blue;Font-size:10pt}
}
</ Style >
</ Head >
< Body >
< Mytag: T1 >
This text is red because it is contained in the mytag: T1 tag.
</Mytag : T1 >
< Mytag: t2 >
This text is green because it is included in the mytag: T2 tag.
</Mytag : T2 >
< Mytag: T3 >
This text is blue because it is included in the mytag: T3 tag.
</ Mytag: T3 >
</ Body >
</ Html >