Full quote from SRD 3.5
Caster Level: The next item in a notational entry gives the caster level of the item, indicating its relative power. The caster level determines the item’s saving throw bonus, as well as range or other level-dependent aspects of the powers of the item (if variable). It also determines the level that must be contended with should the item come under the effect of a dispel magic spell or similar situation. This information is given in the form “CL x,” where “CL” is an abbreviation for caster level and “x” is an ordinal number representing the caster level itself.
For potions, scrolls, and wands, the creator can set the caster level of an item at any number high enough to cast the stored spell and not higher than her own caster level. For other magic items, the caster level is determined by the item itself. In this case, the creator’s caster level must be as high as the item’s caster level (and prerequisites may effectively put a higher minimum on the creator’s level).
Prerequisites: Certain requirements must be met in order for a character to create a magic item. These include feats, spells, and miscellaneous requirements such as level, alignment, and race or kind. The prerequisites for creation of an item are given immediately following the item’s caster level.
A spell prerequisite may be provided by a character who has prepared the spell (or who knows the spell, in the case of a sorcerer or bard), or through the use of a spell completion or spell trigger magic item or a spell-like ability that produces the desired spell effect. For each day that passes in the creation process, the creator must expend one spell completion item or one charge from a spell trigger item if either of those objects is used to supply a prerequisite.
It is possible for more than one character to cooperate in the creation of an item, with each participant providing one or more of the prerequisites. In some cases, cooperation may even be necessary.
If two or more characters cooperate to create an item, they must agree among themselves who will be considered the creator for the purpose of determinations where the creator’s level must be known. The character designated as the creator pays the XP required to make the item.
Typically, a list of prerequisites includes one feat and one or more spells (or some other requirement in addition to the feat).
When two spells at the end of a list are separated by “or,” one of those spells is required in addition to every other spell mentioned prior to the last two.