From AffiliateBang Wiki

elseif is a Midge directive which displays the second argument if the first argument is true. Elseif also checks to see if the previous called if statement was successful, if it was, it will not evaluate the statement. It is possible to nest directives inside of an elseif statement.

Example

[#if,[#global,counter],Hello] [#elseif,[#global,other_counter,Hello as well]

Returns

Prints Hello if the global variable counter is true, if it is not, then other_counter is checked to see if it is true, if it is, then Hello as well is printed.