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Is there a microdata tag to denote whether a value is a number, a string, or a bool?

There is an HTML5 attribute named datetime

which indicates that the value type is datetime. But I don't see a way to tell if the value itemprop

in the tag is a span

string, bool, or a number. Am I correct in saying that there is no such information in the microdata? If so, is there some reason why this possibility should be omitted?

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Only the Microdata spec differs from these value types , which are derived from HTML5 markup:

  • item (if the element has an attribute itemprop

    and itemscope

    )
  • an absolute URL (if itemprop

    specified in a URL property element, for example a

    , video

    etc.)
  • datetime (if itemprop

    specified in the element time

    )
  • string , i.e.
    • for meta

      elements: attribute valuecontent

    • for data

      elements: attribute valuevalue

    • for meter

      elements: attribute valuevalue

    • for every other element: its textContent

Whereas RDFa allows you to specify a data type with an attribute datatype

...

<span property="alive" datatype="xsd:boolean">true</span>
<!-- the value is boolean -->

... Microdata does not offer an attribute like this:

<span itemprop="alive">true</span>
<!-- no way to denote that the value is boolean -->

There was an idea to specify the datatype of Microdata properties in the vocabulary registry , but it seems there was no consensus for that.

What to do?



In their descriptions, dictionaries can be defined that must match / must have their own properties.

The Schema.org dictionary expects (and does not specifically require) certain types. Examples:

The vCard dictionary (as defined by the WHATWG) requires value types. Examples:

One could of course use / create a Microdata dictionary to make such statements about other Microdata dictionaries like RDFS. Schema.org uses RDFa to define its types / properties , and also uses RDFS, but instead of defining a range with rdfs:range

(which would mean that all property values ​​are (also) of this type), they made their own property rangeIncludes

, which does not allow for this inference:

<div typeof="rdf:Property" resource="http://schema.org/free">
  <span class="h" property="rdfs:label">free</span>
  <span property="rdfs:comment">A flag to signal that the publication is accessible for free.</span>
  <span>Domain: <a property="http://schema.org/domainIncludes" href="http://schema.org/PublicationEvent">PublicationEvent</a></span>
  <span>Range: <a property="http://schema.org/rangeIncludes" href="http://schema.org/Boolean">Boolean</a></span>
</div>
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