I think you specify the anchor the same way as you do on your own page but instead of "#top" you would type something like "../differentpage.html#top"
The syntax might be wrong but I know it can be done because I've seen webpages employ this technique for years.
That's a good link to learn it from:
It's really simple though.
Wherever you want the achor, you add:
<a name="anchor_name_here"></a> or <a name="anchor_name_here" />
and wherever you link to it you put:
<a href="other_page.html#anchor_name_here">Your link text here</a>