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About Persisting TZDEFINITION to a Stream to Commit to a Binary Property

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About Persisting TZDEFINITION to a Stream to Commit to a Binary Property

The time zone properties, dispidApptTZDefEndDisplay, dispidApptTZDefRecur, and dispidApptTZDefStartDisplay 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 possible flags for wFlags are TZEFINITION_FLAG_VALID_GUID and TZDEFINITION_FLAG_VALID_KEYNAME. If TZEFINITION_FLAG_VALID_GUID is not set, then the GUID is not present in the stream. In this case, TZDEFINITION_FLAG_VALID_KEYNAME must be set. 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.

See Also

Constants for Exported Outlook APIs

How to: Parse a Stream from a Binary Property to Read the TZDEFINITION Structure

How to: Read Time Zone Properties from an Appointment