html - Can the select option value be of different types? -

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i want know practice select option values.

example

<select name="select">   <option value="0-9">sample</option>   <option value="a-z">sample</option>   <option value="this sample value">sample</option>   <option value="this-is-sample-value">sample</option>   <option value="this_is_sample_value">sample</option>   <option value="this & | sample ** value">sample</option> </select>

i'm little bit confused here. select value same input text , textarea

there no limits real type of data can set in value attribute of option element. characters special meaning in html do, of course, need represented appropriate entities (& &amp; example (although 1 in question meets "followed space character" exception rule)).

the attribute defined containing cdata:

<!element option - o (#pcdata)         -- selectable choice --> <!attlist option   %attrs;                              -- %coreattrs, %i18n, %events --   selected    (selected)     #implied   disabled    (disabled)     #implied  -- unavailable in context --   label       %text;         #implied  -- use in hierarchical menus --   value       cdata          #implied  -- defaults element content --   >

— http://www.w3.org/tr/html4/interact/forms.html#h-17.6

cdata sequence of characters document character set , may include character entities. user agents should interpret attribute values follows:

  • replace character entities characters,
  • ignore line feeds,
  • replace each carriage return or tab single space.

user agents may ignore leading , trailing white space in cdata attribute values (e.g., " myval " may interpreted "myval"). authors should not declare attribute values leading or trailing white space.

for html 4 attributes cdata attribute values, specification imposes further constraints on set of legal values attribute may not expressed dtd.

— http://www.w3.org/tr/html4/types.html#type-cdata

the specification doesn't impose additional limits option element's value attribute.


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