How to encode HTMLHelp topic alias: <?dbhh topicname="some_title" topicid="42"?>

What is the accepted/standard way to encode HTML Help topic alias in 
Docbook?

I was thinking of something like <anchor role="topicalias">, but came upon
<?dbhh ...> from a brief search.

I would like to use a technique that is widely accepted and practiced.

My second question: In the .hhp project file for HTML Help, what is the 
semantic of the part following # in the [ALIAS] section?

i.e. 

[ALIAS]
IDH_TUTORIAL = online_t.htm#1041352

Thanks in advance.