Item changes in events are handled inside the event syntax and has to options:
Item change just adds or removes items. Syntax is eveitemchange
name = item name
add = true --- to add
remove = true --- to remove
producer = "name of the producer" -- producer name
reload = "true" -- causing the page to reload to show the item
That's about it for changes. For checks there are a few options.
check = true or false --- does the item exist true or false
vvar = true or false --- another option same as check but consistent with the rest of the system
girl = "whatgirl" -- 2 options "whatgirl" and "any" (not highly tested let me know if these don't work)
That's all for now. If other features are needed please tell me.