SED Question

[henter2009]

I have the following question about sed and methacaracters:

In the eg number 1, I escaped the +, to get any matches with 1 plus (1 or more characters)
In the eg number 2, I escaped the *, to get any matches with 0 or more characters, but it scape the * and takes it at literal.

Why it doesn't take + literal as well?
How does it really works?
Any help?




1.) sed -ne '/t\+/Ip'

tango
tango   > repeated
balada  > non repeated


2.) sed -ne '/t\*/Ip'

t8
t*
t*