# Annotation Glossary

### A

allow-none

  NULL is OK, both for passing and for returning.

### D

default

  Default parameter value (in case a function which shadows this one via rename-to has fewer parameters).

### E

element-type

  Generics and defining elements of containers and arrays.

### O

optional

  NULL may be passed instead of a pointer to a location.

out

  Parameter for returning results. Default is transfer full.

### P

Private

  An interface that can be used within the GNOME stack itself, but that is not documented for end-users. Such functions should only be used in specified and documented ways.

### S

Stable

  The intention of a Stable interface is to enable arbitrary third parties to develop applications to these interfaces, release them, and have confidence that they will run on all minor releases of the product (after the one in which the interface was introduced, and within the same major release). Even at a major release, incompatible changes are expected to be rare, and to have strong justifications.

### T

transfer container

  The caller owns the data container, but not the data inside it.

transfer full

  The caller owns the data, and is responsible for free it.

transfer none

  The data is owned by the callee, which is responsible of freeing it.

### U

Unstable

  Unstable interfaces are experimental or transitional. They are typically used to give outside developers early access to new or rapidly changing technology, or to provide an interim solution to a problem where a more general solution is anticipated. No claims are made about either source or binary compatibility from one minor release to the next. The Unstable interface level is a warning that these interfaces are subject to change without warning and should not be used in unbundled products. Given such caveats, customer impact need not be a factor when considering incompatible changes to an Unstable interface in a major or minor release. Nonetheless, when such changes are introduced, the changes should still be mentioned in the release notes for the affected release.