BOM()
 Determines the date of the first day of a month
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 Syntax

     BOM([<dDate>]) --> dBeginningOfMonth

 Argument

     <dDate>  Designates a date for which the first day of the month that
     contains this date, is determined.  The default is the system date.

 Returns

     BOM() returns the first day of the month in which <dDate> lies.

 Description

     BOM() allows you to determine the first day of the month that contains
     <dDate>.  This allows you to determine how many days have past since the
     beginning of the month.

 Note

     .  If no date is passed, then the function automatically uses the
        system date.  An empty date parameter always returns an empty date.

 Example

     Display the elapsed days in the current month:

     ? DATE() - BOM()