About Persisting TZDEFINITION to a Stream to Commit to a Binary Property
The time zone properties, PidLidAppointmentTimeZoneDefinitionEndDisplay, PidLidAppointmentTimeZoneDefinitionRecur, and PidLidAppointmentTimeZoneDefinitionStartDisplay are binary named properties, each of which contains a stream that maps to the persisted format of a TZDEFINITION structure.
This topic describes a little endian format that can be used when persisting TZDEFINITION to a stream to commit to one of three binary properties. Use the same endian format in a parser to interpret a stream value obtained from one of these properties.
BYTE bMajorVersion; // breaking change BYTE bMinorVersion; // extensibility WORD cbHeader; // size of following data until TZREG sub structure WORD wFlags; if (TZDEFINITION_FLAG_VALID_GUID) GUID guid; // guid if (TZDEFINITION_FLAG_VALID_KEYNAME) WORD cchKeyName; // does not include null char WCHAR rgchKeyName; // not null terminated WORD cRules; // number of rules // for each rule BYTE bMajorVersion; // breaking change BYTE bMinorVersion; // extensibility WORD cbRule; // size of following data WORD wFlags; // flags SYSTEMTIME stStart; // GMT when this rule starts // Following are the fields of the TZREG sub structure long lBias; // offset from GMT long lStandardBias; // offset from bias during standard time long lDaylightBias; // offset from bias during daylight time SYSTEMTIME stStandardDate; // time to switch to standard time SYSTEMTIME stDaylightDate; // time to switch to daylight time
The major version number is used to make a breaking change. Clients that are unfamiliar with the major version number should treat the property as if it is not there. Clients writing the structure should specify the constant TZ_BIN_VERSION_MAJOR.
The minor version number is used for extensibility. Clients that are unfamiliar with the minor version number should read the data that they understand, and skip over the data that might be appended to each rule or to the overall stream. Clients writing the structure should specify the constant TZ_BIN_VERSION_MINOR.
If a parser does not understand the major version of the header, it should not read the rest of the structure and behave as if the data is missing. If a parser does not understand the minor version of the header, it should use cbHeader to ignore the portions that it does not understand and advance to read the portions of the stream that it understands.
The value of wFlags is always TZDEFINITION_FLAG_VALID_KEYNAME. The key name has a maximum size of MAX_PATH.
If a parser does not recognize the major version of a rule, the client should ignore the rule, and use cbRule to advance to the next rule. If a parser does not recognize the minor version of a rule, the client should only parse the parts of the rule that it understands.
When persisting a TZDEFINITION structure to a stream, a parser should not try to write any information that it does not understand.
The maximum number of rules is 1024.
Note that the TZREG structure is persisted here differently than when persisted alone, so the same code cannot be used to parse it.