Short version: Can anyone send me a guide that gives a really detailed description of how formatting works in Word? All the hidden mark-ups, stuff where I might need to dig into the XML of a .docx file in order to really understand it.

Long version: I'm working on a tool that takes a big Word document as a template, cuts out sections that aren't relevant to the final document I'm making, and spits a Word document back at me with the sections removed. However, I'm having persistent problems with the formatting of the text being incorrect immediately after a removed section. This has not been a problem in previous versions of this, and the third-party program has not changed, so I'm thinking that this is probably a problem with my formatting of the "template" Word document.

What seems to happen is that after a section is removed, the format will jump to something else. For example, I'll be writing a section where everything is in 11pt indigo-coloured font, and then after a small section is removed, it'll jump to 12pt black font(which is the document's default) until the end of the paragraph. At that point, the correct formatting will take over again.

The most complex instance of the problem is as follows: In the original Word document, there's the following text line-by-line:
(1pt white text tag, defining the end of the section which is being removed)
(8pt blank line)
(14pt black header-formatted text, with some parts highlighted)
(11pt blank line)
(11pt white text with dark red highlight, followed by 11pt white text with red highlight)

The following is what results after the removal:
(8pt blank line)
(14pt white header-formatted text, with some parts highlighted)
(11pt blank line)
(1pt white text with dark red highlight, followed by 11pt white text with red highlight)

The formatting of the removed section is carrying through in ways I do not understand, and that's causing issues with the final product. This is supposed to generate documents that go to our best clients, and the tool that creates them has to be used by my whole department, so it can't have issues like this when my updates are going live.

Thank you.