Use of NULL to initialize $ Session Vars

Is this okay?

[neophyte]

The project I'm currently sweating through necessitates a fairly long list of $_Session Vars. When the first page of this app loads it initializes these vars with "Null".

I could use anything to initialize these vars, but I've used NULL for no specific reason and so far, so good. But is there anything that I should be worried about when using NULL for initialization?

When others init $_Session vars, what do you use?

Neophyte

[eelixduppy]

>>Is this okay?

I don't see any problems with it. Generally I let the var take its default value:

$var;