2.2.12 [W3C-EPUB3] Section 4.4.2.4.1. Usage

C0015: The rendition:spread property is not supported and is ignored

The specification states:

 › 4.4.2.4.1 Usage
  
 When the rendition:spread property is specified on a meta element, it indicates that the 
 intended Synthetic Spread behavior applies globally for the given Rendition (i.e., for 
 all spine items).

EdgeHTML Mode

The rendition:spread property is not supported and is ignored.