2.1.5 [W3C-EPUB3] Section 3.4.6. The DCMES Optional Elements

V0009: Leading and trailing whitespace is not trimmed

The specification states:

 › 3.4.6 The DCMES Optional Elements
  
 All elements from the [DCMES] element set — except for identifier, language and title, as 
 defined above — are designated as optional. These elements all conform to the following 
 generalized definition:
 ...
 Reading Systems must trim all leading and trailing whitespace from the element value, as 
 defined by the XML specification [XML], before processing the value.

EdgeHTML Mode

Leading and trailing whitespace is not trimmed.