>>>The number one rule: The number one rule for me is to trust in glyphs. I used to depend on entities back the HTML 4.x days, but now it's all about Unicode glyphs.

>>>No-break space: XML (namely XHTML) will collapse spaces (entered by the spacebar). To avoid this, use Alt+0160 (the no-break space). The no-break space is also the no-collapse space!