PSA(IEXP) (BOOLEAN)

 Function
  Determine whether or not a given PSA is installed.

 Syntax
  PSA(num)

   num = An integer expression with the number of the PSA to check for
         the existence of.

 Return Type & Value
  BOOLEAN
  Returns TRUE if the specified PSA exists or FALSE if it doesn't exist
  for the following values of num:

       1 = Alias PSA;
       2 = Verification PSA.
       3 = Address PSA;
       4 = Password PSA;
       5 = Statistics PSA.
       6 = Notes PSA.

 Remarks
  This function allows you to determine whether or not a given PCBoard
  Supported Allocation (PSA) is installed.  For each of the six PSAs it
  will return TRUE if installed or FALSE if not installed.  It is useful
  when you want to write a generic PPL application that will access one
  or more PSAs that may or may not be installed.

 Examples
  STRING ynStr(1)
  LET ynStr(0) = "NO"
  LET ynStr(1) = "YES"
  PRINTLN "       Alias Support Enabled?  ",ynStr(PSA(1))
  PRINTLN "Verification Support Enabled?  ",ynStr(PSA(2))
  PRINTLN "     Address Support Enabled?  ",ynStr(PSA(3))
  PRINTLN "    Password Support Enabled?  ",ynStr(PSA(4))
  PRINTLN "  Statistics Support Enabled?  ",ynStr(PSA(5))
  PRINTLN "       Notes Support Enabled?  ",ynStr(PSA(6))