Help needed to understand JLS ?5.14

Can someone please help me to understandJLS ?5.14 (http://java.sun.com/docs/books/jls/third_edition/html/expressions.html#15.14), it says:

Postfix expressions include uses of the postfix ++ and -- operators. Also, as discussed in ?5.8, names are not considered to be primary expressions, but are handled separately in the grammar to avoid certain ambiguities. They become interchangeable only here, at the level of precedence of postfix expressions.

PostfixExpression:

Primary

ExpressionName

PostIncrementExpression

PostDecrementExpression

Questions:

1. According to documentation above, "Primary" & "ExpressionName" are also considered as "PostfixExpression". Can someone please explain with some grammar examples?

2. The statement "They become interchangeable only here, at the level of precedence of postfix expressions." What is exactly interchangeable? Where can I find the level of precedence of postfix expressions?

Thank you for your time.

[1049 byte] By [baptistchena] at [2007-11-27 6:36:40]
# 1
Are these questions too hard to answer?
baptistchena at 2007-7-12 18:04:36 > top of Java-index,Java Essentials,Java Programming...
# 2
Well I wouldn't consider myself any expert in language grammars and thus I don't really want to take any position considering this spec. Even though I know how to use the ++ and -- operators, this kind of documentation always remains cryptic :)
Dalzhima at 2007-7-12 18:04:36 > top of Java-index,Java Essentials,Java Programming...