2.1.33 [W3C-HTML52] Section 4.7.16.2. Processing model

V0128: The usemap attribute does not do a case-sensitive match for the appropriate image map

The specification states:

 ... Processing model
  
     If an img element ... has a usemap attribute specified, user agents must process it 
     as follows:

EdgeHTML Mode

The usemap attribute does not do a case-sensitive match for the appropriate image map.

V0127: If an image does not load, a valid image map will still be applied to the missing image, and not in a way that associates the image with the text

The specification states:

 ... Processing model
     ...
     If the user agent intends to show the text that the img element represents, then it 
     must use the following steps.
         ...
         3.  Each remaining area element in areas represents a hyperlink. Those hyperlinks 
             should all be made available to the user in a manner associated with the text 
             of the img.

EdgeHTML Mode

If an image does not load, a valid image map will still be applied to the missing image, and not in a way that associates the image with the text.