The _XSETTINGS_SETTINGS property is of form 8 and type _XSETTINGS_SETTINGS. The contents are a
1 CARD8 byte-order 3 unused 4 CARD32 SERIAL 4 CARD32 N_SETTINGS
Followed by N_SETTINGS settings records, which have a header:
1 SETTING_TYPE type 1 unused 2 n name-len n STRING8 name P unused, p=pad(n) 4 CARD32 last-change-serial
Where SETTING_TYPE is
0 XSettingsTypeInteger 1 XSettingsTypeString 2 XSettingsTypeColor
followed by the body. If TYPE = XSettingsTypeString the body is:
4 n value-len n STRING8 value P unused, p=pad(n)
If TYPE == XSettingsTypeInteger, then the body is:
4 INT32 value
If TYPE == XSettingsTypeColor, then the body is:
2 CARD16 red 2 CARD16 green 2 CARD16 blue 2 CARD16 alpha
If the setting does not need the alpha field, it should be set to 65535.
Setting names must be confined to the ascii characters:
'A'-'Z' 'a'-'z' '0'-'9' '_' and '/'
With the additional restrictions that '/' cannot appear in the leading or trailing position, that two occurences of '/' cannot be consecutive, and that the first character of the name, and and the first character after a slash cannot be one of '0'-'9'. Names may not be empty.
"GTK/colors/background0" "_background" "_111"
are legitimate names, while
"/" "_background/" "GTK//colors" ""
Are not legitimate names.
The names, types, contents, and default values of standard settings will be separately agreed upon.
Names beginning with 'Net/' and case variants of that string are reserved and must not be used without prior agreement.
The 'serial' field and and the 'last-change-serial' field of the each settings record can be used to tell which settings have changed since the last time a client retrieved the _XSETTINGS_SETTINGS property. Each time the client retrieves the contents of the _XSETTINGS_SETTINGS property it should store the contents of the 'serial' field. When it next retrieves the property, any settings whose 'last-change-serial' is greater than the stored value.
(Careful clients will make provisions for wrap-around of the serial field. This is, however, not expected to happen in practice.)