isvalid
| isvalid | 
  Purpose
 
 Check whether a date, time or datetime is valid.
 
  Synopsis
 
function isvalid(d:date):boolean
 function isvalid(t:time):boolean
 function isvalid(dt:datetime):boolean
 
  Arguments
 
| 
     d 
     | 
     A
     date object
     | 
| 
     t 
     | 
     A
     time object
     | 
| 
     dt 
     | 
     A
     datetime object
     | 
  Return value
 
 True if the argument is valid.
  Further information
 
  A
 date is valid if its month number is in the range 1-12 and its day number is in the range 1-31 and is compatible with its month number (for instance 2006-2-29 is not a valid date). A
 time is valid if it is positive and smaller than an entire day. A
 datetime is valid if both its date part and its time part are valid.
 
  Module
 
 
