Linking to PDFs and still being accessible

I'm just about to link to a PDF and want to make sure that the link abides by accessibility guidelines for the benefit of my web users.

Now I know from Steve Krug's book and other accessibility nuggets that there are some basic rules for ALL links and also some specific PDF relevant things (as you can see, the following is just an index of Jakob Nielsen's website!).

• Only use PDFs if you have to. Presenting in HTML format is often a lot more user friendly.
• The link design should be obvious (Jakob Nielson has a whole article on this) - personally i think a different colour and underlined is the most accessible (i bet you just tried to click that!). However links can still suit design, check out the BBC website, it's really obvious what's a link and what's not.
• Create gateway pages for each PDF file so users can see what they are about to get (Jakob on gateways)
• If you are linking to a PDF on someone else's website don't do so directly. Link to their gateway page, there are a number of reasons why, again Jakob sums it up best.
• Ensure the PDF opens in a new browser window (Jakob on opening files from a web page).
• Tell users that it's a PDF and what file size it is.
• Explain to users what a PDF is and give them a link to the Adobe website to download Adobe Reader.

Now it's this last point that i've been stuck on. I'm just linking to a tube map and i don't want a whole gateway page (maybe i really should) with introduction etc. The BBC go all the way and are comprehensive with their PDF links (their annual reports [was] a good example [the page has now been changed]), hence the advantage of creating gateway pages - you have space to explain PDF files.

So against my own advice i'm going to compromise and use a table to format the following side by side (these are pretend links for the purposes of this post...).

Download tube directions (PDF, 300 KB)

More information on PDF files

1. So STOP!
2. Do you need to have a pdf?
3. If you do make sure you give it a gateway page.
4. Explain about PDFs to your users.

UPDATE (2/11): After all that i revisited my pdf of tube directions this week and decided to put it on my site in a downloads section (in other words a gateway page) as it's so much tidier. Should have listened to my own advice ;)