I'm a little confused with regards to magic item creation. The general rule on p. 548 it says...
"Note that all items have prerequisites in their descriptions. These prerequisites must be met for the item to be created. Most of the time, they take the form of spells that must be known by the item’s creator (although access through another magic item or spellcaster is allowed). The DC to create a magic item increases by +5 for each prerequisite the caster does not meet. The only exception to this is the requisite item creation feat, which is mandatory. In addition, you cannot create spelltrigger and spell-completion magic items without meeting their spell prerequisites."
The first part of the passage suggests that access through another magic item or spellcaster is allowed, but the last sentence suggests it isn't for "spelltrigger and spell-completion magic items". Aren't a large proportion of magic items "spelltrigger and spell-completion magic items"? This would most certainly include potions, wands, and scrolls, but what about rods (metamagic) and staves (that cast many spells)? What about rings which duplicate spell effects (e.g. invisibility)?
I find this to be very confusing language. Can anyone please clarify for me? Thanks.
Keith