Schema.org, HTML5 and the datetime format: how do I get it to validate?

Question

Schema.org says this,

The opening hours for a business. Opening hours can be specified as a weekly time range, starting with days, then times per day. Multiple days can be listed with commas ',' separating each day. Day or time ranges are specified using a hyphen '-'. Days are specified using the following two-letter combinations: Mo, Tu, We, Th, Fr, Sa, Su. Times are specified using 24:00 time. For example, 3pm is specified as 15:00. Here is an example: <time itemprop="openingHours" datetime="Tu,Th 16:00-20:00">Tuesdays and Thursdays 4-8pm. If a business is open 7 days a week, then it can be specified as <time itemprop="openingHours" datetime="Mo-Su">Monday through Sunday, all day</time>.

However, when I use that time format I get this on the W3C's validator,

Error Line 1, Column 2898: Bad value Mo-Fr 09:00-17:00 for attribute datetime on element time: The literal did not satisfy the time-datetime format.

…ingHours" datetime="Mo-Fr 09:00-17:00">Mon - Fri; 9 AM - 5 PM (CST)
…

I've tried with and without padding a 0 on 9:00.

Answer 1

You don't say what you are using to validate your markup.

According to this post StackOverflow: schema.org openinghours some validators don't accept the datetime format suggested by schema.org and instead expect the ISO 8601 format which doesn't support day of the week.

Another solution suggests using a much more granular format for your opening hours:

<div itemscope itemtype="http://schema.org/Place" itemid="#store">
  <link itemprop="http://www.w3.org/1999/02/22-rdf-syntax-ns#type" 
        href="http://purl.org/goodrelations/v1#Location" />
  <span itemprop="name">Hepp's Happy Burger Restaurant</span>
  <div itemprop="http://purl.org/goodrelations/v1#hasOpeningHoursSpecification" itemscope 
       itemtype="http://purl.org/goodrelations/v1#OpeningHoursSpecification">
Opening hours: Mo-Fri,
     <link itemprop="hasOpeningHoursDayOfWeek" 
           href="http://purl.org/goodrelations/v1#Monday" />
     <link itemprop="hasOpeningHoursDayOfWeek" 
           href="http://purl.org/goodrelations/v1#Tuesday" />
     <link itemprop="hasOpeningHoursDayOfWeek" 
           href="http://purl.org/goodrelations/v1#Wednesday" />
     <link itemprop="hasOpeningHoursDayOfWeek" 
           href="http://purl.org/goodrelations/v1#Thursday" />
     <link itemprop="hasOpeningHoursDayOfWeek" 
           href="http://purl.org/goodrelations/v1#Friday" />
     <meta itemprop="opens" content="08:00:00">8:00 a.m. -
     <meta itemprop="closes" content="20:00:00">8:00 p.m.
  </div>
</div>