# Annotation Glossary

### A

allow-none

  NULL is OK, both for passing and for returning.

### E

element-type

  Generics and defining elements of containers and arrays.

### I

in

  Parameter for input. Default is transfer none.

### O

out

  Parameter for returning results. Default is transfer full.

out callee-allocates

  Out parameter, where caller must allocate storage.

### S

scope async

  The callback is valid until first called.

### T

transfer full

  Free data after the code is done.

transfer none

  Don't free data after the code is done.