Local nodes are always linked in with a type 1 link - that is, as an attribute.
With global nodes it is important to think of the type of link being made. Really the conventions used can only be appreciated with experience and browsing of the system. The relevance of making the link must be considered - obscure features may be entirely valid - for example Janeway lesion as a very rare symptom of infective endocarditis - and common features may perhaps be irrelevant or confusing to include - for example headache as a symptom of influenza.
Annotations allow you to add information to this page that would be handy to have on hand during a consultation. E.g. a website or number. This information will always show when you visit this page.