Q:

What is the pipe character "x|y)" in the case statement?

In a script /etc/network/if-up.d/avahi-autoipd in my system, I find statements like this:
case "$ADDRFAM" in
  inet|NetworkManager) ;;
  *) exit 0
esac

case "$METHOD" in
static|dhcp|NetworkManager) ;;
*) exit 0
esac

The pipe character | seems like the logic "or", but I can't find this rule in the guide. I can only find | used as the command pipe and the "bitwise or" for the arithmetic integer. 
Can anyone tell me what's the usage in this case? 

A:

In the pattern clauses of a case statement, | means precisely or.
From the bash manual on case:

The syntax of the case command is:

case word in [ [(] pattern [| pattern]…) command-list ;;]… esac 

The ‘|’ is used to separate multiple patterns, and the ‘)’ operator terminates a pattern list.

