# Annotation Glossary

### A

allow-none

  NULL is OK, both for passing and for returning.

array

  Parameter points to an array of items.

### C

closure

  This parameter is a 'user_data', for callbacks; many bindings can pass NULL here.

### E

error-domains

  Typed errors. Similar to throws in Java.

### I

in

  Parameter for input. Default is transfer none.

### O

out

  Parameter for returning results. Default is transfer full.

### 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.