2.1.4 [W3C-EPUB3] Section 3.4.5. The DCMES language Element
V0008: Leading and trailing whitespace is not trimmed
The specification states:
› 3.4.5 The DCMES language Element The [DCMES] language element specifies the language of the content of the given Rendition. ... Reading Systems must trim all leading and trailing whitespace from the element value, as defined by the XML specification [XML], before processing the value.
Leading and trailing whitespace is not trimmed.