XML in a Nutshell, 3rd Edition

Matching Descendants, Children, and Siblings

An element name A followed by another element name B matches all B elements that are descendants of A elements. For example, this rule matches quantity elements that are descendants of ingredients elements, but not other ones that appear elsewhere in the document:

ingredients quantity {font-size: medium}

If the two element names are separated by a greater-than sign (>), then the second element must be an immediate child of the first in order for the rule to apply. For example, this rule gives quantity children of ingredient elements the same font-size as the ingredient element:

ingredient > quantity {font-size: inherit}

If the two element names are separated by a plus sign (+), then the second element must be the next sibling element immediately after the first element. For example, this style rule sets the border-top-style property for only the first story element following a directions element:

directions + story {border-top-style: solid}