The best practice in naming anything within the Miva environment is to only use the numerals 0-9; the alphabet a-z, the dash -, and the underscore _
This includes static page filenames, pagecodes, category codes/names, product codes/names, custom field codes/names and attribute codes, just to name a few.

Using anything else [including spaces] can interfere with several areas of your store/site, like the database, the dynamically generated MivaScript, various other programming scripts and browser interpretation. The only exception to using spaces would be within the category/product names only, and even then you should use some server support to correct the way the browser interprets them so your URL’s are kept search engine friendly.

Search strings using bad custom field codes/names will cease to function properly and in certain instances can cause other html code to behave badly.

Product and category codes using erroneous characters can cause severe database corruption.