best practice recommendations for naming chunks, snippets, etc.

I’ve been instinctively following pretty strict rules for naming stuff... aside from Templates, I’ve been sticking to alphanumeric characters and underscores. No spaces.
I’m writing a little tutorial right now, and was about to recommend this approach to naming things. Should I? It never even occurred to me before that I could do otherwise. Are there any potential pitfalls to giving your chunks etc. filenames that contain spaces and/or non-alphanumerics? Just curious.

<@developers!>
For snippets, plugins etc. - NEVER use variables/parameters
that also are HTML character tags.
I.e.

&lang=`` / ⟨

Should be good practice for Revo too, I assume.
http://modxcms.com/forums/index.php/topic,39039.msg271912.html#msg271912

[[Snippet?
    &html=`<a href="[[~12]]">This is ok in Revo</a>`
]]