%%

ALPHA=[A-Za-z]
DIGIT=[0-9]
NON_NEW_LINE_WHITE_SPACE=[\  \t\b\012]
SAFECHAR=[^\"\;,:\^C]
QSAFECHAR=[^\^C\"]
XNAME=X-(({ALPHA}|{DIGIT}){3}({ALPHA}|{DIGIT})*)*({ALPHA}|{DIGIT}|-)
PARAMVALUE=({SAFECHAR}*|\"{QSAFECHAR}*\")
XPARAM={XNAME}={PARAMVALUE}(,{PARAMVALUE})*
DATE={DIGIT}{8}
TIME=({DIGIT}{2}:{DIGIT}{2}:{DIGIT}{2}|{DIGIT}{2}:{DIGIT}{2}:{DIGIT}{2}Z)
DATETIME={DATE}T{TIME}
TSAFECHAR=[^\^C\;,:\\]
ESCAPECHAR=(\\\\|\\\;|\\,|\\N|\\n)
ITEXT=({TSAFECHAR}|:|\"|{ESCAPECHAR}|\r\f{NON_NEW_LINE_WHITE_SPACE})
URI=\".*\"
ALTREP=ALTREP\={URI}
LANGUAGE=LANGUAGE\={ITEXT}
TZIDPARAM=TZID\=\/*{SAFECHAR}*\r\f
FLOAT=(+|-)*{DIGIT}+\.{DIGIT}+
CNPARAM=CN\={PARAMVALUE}
DIRPARAM=DIR\=\"{URI}\"
SENTBYPARAM=SENT\-BY\=\"{URI}\"
INTVALUE=(+|-)*{DIGIT}+
STATVALUE=(TENATIVE|CONFIRMED|CANCELLED|NEEDS\-ACTION|COMPLETED|IN\-PROCESS|DRAFT|FINAL)
TRANSPVALUE=(OPAGUE|TRANSPARENT)


%%

<YYINITIAL> ^VERSION
<YYINITIAL> ^PRODID
<YYINITIAL> ^CALSCALE
<YYINITIAL> ^BEGIN:VEVENT\r\f
<YYINITIAL> ^BEGIN:VTODO\r\f
<YYINITIAL> ^BEGIN:VFREEBUSY\r\f
<YYINITIAL> ^BEGIN:VJOURNAL\r\f
<YYINITIAL> ^BEGIN:VTIMEZONE\r\f
<VERSION> :2"."0\r\f
<VEVENT> <VTODO> <VJOURNAL> CLASS
<VEVENT> <VTODO> <VJOURNAL> CREATED
<VEVENT> <VTODO> <VJOURNAL> DESCRIPTION
<VEVENT> <VTODO> <VJOURNAL> <VFREEBUSY> DTSTART
<VEVENT> <VTODO> GEO
<VEVENT> <VTODO> <VJOURNAL> <VTIMEZONE> LAST\-MODIFIED
<VEVENT> <VTODO> LOCATION
<VEVENT> <VTODO> <VJOURNAL> <VFREEBUSY> ORGANIZER
<VEVENT> <VTODO> PRIORITY
<VEVENT> <VTODO> <VJOUNRAL> <VFREEBUSY> DTSTAMP
<VEVENT> <VTODO> <VJOURNAL> SEQUENCE
<VEVENT> <VTODO> <VJOURNAL> STATUS
<VEVENT> <VTODO> <VJOURNAL> SUMMARY
<VEVENT> TRANSP
<VEVENT> <VTODO> <VJOURNAL> <VFREEBUSY> UID
<VEVENT> <VTODO> <VJOUNRAL> <VFREEBUSY> URL
<VEVENT> <VTODO> <VJOURNAL> RECURRENCE\-ID
<VEVENT> <VFREEBUSY> DTEND
<VEVENT> <VTODO> <VFREEBUSY> DURATION
<VEVENT> <VTODO> <VJOURNAL> ATTACH
<VEVENT> <VTODO> <VJOURNAL> <VFREEBUSY> ATTENDEE
<VEVENT> <VTODO> <VJOURNAL> CATEGORIES
<VEVENT> <VTODO> <VJOURNAL> <VFREEBUSY> COMMENT
<VEVENT> <VTODO> <VJOURNAL> <VFREEBUSY> CONTACT
<VEVENT> <VTODO> <VJOURNAL> EXDATE
<VEVENT> <VTODO> <VJOURNAL> EXRULE
<VEVENT> <VTODO> <VJOURNAL> <VFREEBUSY> REQUEST\-STATUS
<VEVENT> <VTODO> <VJOURNAL> RELATED-TO
<VEVENT> <VTODO> RESOURCES
<VEVENT> <VTODO> <VJOURNAL> RDATE
<VEVENT> <VTODO> <VJOURNAL> RRULE
<VTODO> COMPLETED
<VTODO> PERCENT-COMPLETE
<VTODO> DUE
<VFREEBUSY> FREEBUSY
<VTIMEZONE> TZID
<VTIMEZONE> TZURL
<VTIMEZONE> BEGIN:STANDARD\r\f
<VTIMEZONE> BEGIN:DAYLIGHT\r\f
<CLASS> <CREATED> <DESCRIPTION> <DTSTART> <GEO> <LASTMOD> <ORGANIZER> <PRIORITY> <DTSTAMP> <SEQUENCE> <STATUS> <SUMMARY> <TRANSP> <UID> <URL> \;{XPARAM}
<CLASS> :(PUBLIC|PRIVATE|CONFIDENTIAL|{XNAME})
<CREATED> <DTSTAMP> :{DATETIME}\r\f
<DESCRIPTION> <LOCATION> <SUMMARY> \;{ALTREP}
<DESCRIPTION> <LOCATION> <ORGANIZER> <SUMMARY> \;{LANGUAGE}
<DESCRIPTION> <LOCATION> <SUMMARY> <UID> :{ITEXT}\r\f
<DTSTART> \;VALUE\=(DATE-TIME|DATE)
<DTSTART> \;{TZIDPARAM}
<DTSTART> :({DATE}|{DATETIME})\r\f
<GEO> :{FLOAT}\;{FLOAT}\r\f
<LASTMOD> :{DATETIME}\r\f
<ORGANIZER> \;{CNPARAM}
<ORGANIZER> \;{DIRPARAM}
<ORGANIZER> \;{SENTBYPARAM}
<ORGANIZER> \;\"{URI}\"\r\f
<PRIORITY> <SEQUENCE> :{INTVALUE}\r\f
<STATUS> :{STATVALUE}\r\f
<TRANSP> :{TRANSPVALUE}\r\f
<URL> :{URI}\r\f