Identifiers

[Kamal]

How do you attach a duration (or other notation) to an identifier?

Example:
I have:
<a c e>8 <a c e>16[ <a c e>]

I want to use "<a c e>" as an identifier so I tried the following but
it didn't work:

var = { < a c e> }

\score {
{ \var \var16[ \var16] }
}

I am using lilypond 2.8.6