There's also the alternative link type, "href" or "link". Both do exactly the same thing. The advantage, such as it is, is that you don't need to carefully craft the HTML. Examples:

[href://?node_id=6364&user=gaal|Nodes gaal wrote]

Nodes gaal wrote

[link://?node_id=6364&user=gaal|Nodes gaal wrote]

Nodes gaal wrote

In principle, if you manually create a HTML link, you really ought to escape the ampersand, or use use the alternative semicolon instead. Because "user" isn't a recognized entity name, you can generally disregard this advice, though technically, your HTML won't validate. If you even care about that.

If you use the link types as given above, the site will do the escaping for you.