("distributed fixity"?) A description of an operator represented by multiple symbols before, between, and/or after the arguments.
The classical example is the C conditional operator, "?:" which is written
E1 ? E2 : E3
If E1 is true it returns E2 otherwise it returns E3. Several functional programming languages, e.g. Hope, Haskell, have similar operators ("if E1 then E2 else E3").
Objective C messages are effectively distfix operator applications:
getRow:row andColumn:col ofCell:cell
is a message with three arguments, row, col, and cell.