Unable to understand 'BYSETPOS' in the Docs #89

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1. boryn commented on Sep 17, 2021

   

   boryn

   on Sep 17, 2021

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   Hi @marcoczen!

   With the example of "FREQ=MONTHLY;INTERVAL=1;BYSETPOS=-1;BYDAY=MO,TU,WE,TH,FR;BYMONTHDAY=26,27,28,29,30,31;COUNT=12"
   you have a set of occurences falling at 26-31 of the month and only on MO,TU,WE,TH,FR.

   BYSETPOS is not a rule by itself, actually it limits the rule. It means take the n-th instance from the calculated instances corresponding to the rest of the rule. So in our case it means take the last day at the end of the month of the working days.

   Hope it clarifies :)
2. marcoczen commented on Sep 17, 2021

   

   marcoczen

   on Sep 17, 2021

   Last edited by marcoczen

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   Hi @boryn ,

   BYSETPOS is not a rule by itself, actually it limits the rule.

   Noted ...

   It means take the n-th instance from the calculated instances corresponding to the rest of the rule

   -1 ? nth instance ... but its not 2 or 3 or 1 but -1 ?
   Also, if i want the last of an occurence, its -1 ? Cant it be +366 or +365 ?

   Also bysetpos works on byday or bymonthday ? or both ?

   Sorry if i am a dumbass....
3. marcoczen commented on Sep 17, 2021

   

   marcoczen

   on Sep 17, 2021

   Last edited by marcoczen

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   Background info for the next noob ...

   From https://datatracker.ietf.org/doc/html/rfc5545#section-3.8.5

   The BYSETPOS rule part specifies a COMMA-separated list of values
   that corresponds to the nth occurrence within the set of
   recurrence instances specified by the rule. BYSETPOS operates on
   a set of recurrence instances in one interval of the recurrence
   rule. For example, in a WEEKLY rule, the interval would be one
   week A set of recurrence instances starts at the beginning of the
   interval defined by the FREQ rule part. Valid values are 1 to 366
   or -366 to -1. It MUST only be used in conjunction with another
   BYxxx rule part. For example "the last work day of the month"
   could be represented as:

      FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;BYSETPOS=-1
   
     Each BYSETPOS value can include a positive (+n) or negative (-n)
     integer.  If present, this indicates the nth occurrence of the
     specific occurrence within the set of occurrences specified by the
     rule.
   
4. Repository owner locked and limited conversation to collaborators on Sep 17, 2021
5. tplaner

   closed this as completedon Sep 17, 2021