Represents a set of attributes that are stored with an item.
These schemas are used for interoperability between various services storing the same types of items.
Each schema has a name like `org.gnome.keyring.NetworkPassword`, and defines a set of attributes, and types (string, integer, boolean) for those attributes.
Attributes are stored as strings in the Secret Service, and the attribute types simply define standard ways to store integer and boolean
values as strings. Attributes are represented in libsecret via a [structGLib.HashTable] with string keys and values. Even for
values that defined as an integer or boolean in the schema, the attribute values in the [structGLib.HashTable] are strings.
Boolean values are stored as the strings 'true' and 'false'. Integer values are stored in decimal, with a preceding negative sign for
negative integers.
Schemas are handled entirely on the client side by this library. The name of the schema is automatically stored as an attribute on the item.
Normally when looking up passwords only those with matching schema names are returned. If the schema flags contain the
`SECRET_SCHEMA_DONT_MATCH_NAME` flag, then lookups will not check that the schema name matches that on the item, only the schema's
attributes are matched. This is useful when you are looking up items that are not stored by the libsecret library. Other libraries such as
libgnome-keyring don't store the schema name.
Additional schemas can be defined via the Schema structure like this:
```c // in a header:
const SecretSchema * example_get_schema (void) G_GNUC_CONST;
define EXAMPLE_SCHEMA example_get_schema
// in a .c file
const SecretSchema * example_get_schema (void) { static const SecretSchema the_schema = { "org.example.Password", SECRET_SCHEMA_NONE, { { "number", SECRET_SCHEMA_ATTRIBUTE_INTEGER }, { "string", SECRET_SCHEMA_ATTRIBUTE_STRING }, { "even", SECRET_SCHEMA_ATTRIBUTE_BOOLEAN }, { NULL, 0 }, } }; return &the_schema; } ```