The most basic keywords of the ITP Language are the keywords that allow you to open and close an ITP Document or an ITP section in a document.
An entire document can be built up with ITP Language, but you can also insert smaller sections of ITP language in a 'regular' document. In both cases the keywords BEGIN and END define where the ITP Language part begins and ends and therefore where the document has to connect to the database you are working with.
Within such a document or section actions are performed in order to build your document. Between DO and OD you insert the actions you want to perform in order to give a scope to the actions you want to use; a document or section (Area between BEGIN and END) can have more than one DO.. ...OD part.