"EPUB can be viewed as simply defining a specialization of Web content that assures that a collection of content items has the needed properties of completeness and logical structure, and does so in a standard way so that other processing tools and services can reliably create, manipulate, and present such collections."
"EPUB can be viewed as simply defining a specialization of Web content that assures that a collection of content items has the needed properties of completeness and logical structure, and does so in a standard way so that other processing tools and services can reliably create, manipulate, and present such collections."
delete "so" before "that other processing tools"