Question on funcion and npar

Dear everyone,

The following function, taken from Quick-R, gets measures of central 
tendency and spread for a numeric vector x.

I can't figure out what the argument npar means in each instance.
Any tips will be most appreciated.

mysummary <- function(x, npar=TRUE, print=TRUE) {
   if (!npar) {
     center <- mean(x); spread <- sd(x)
   } else {
     center <- median(x); spread <- mad(x)
   }
   if (print & !npar) {
     cat("Mean=", center, "\n", "SD=", spread, "\n")
   } else if (print & npar) {
     cat("Median=", center, "\n", "MAD=", spread, "\n")
   }
   result <- list(center=center,spread=spread)
   return(result)
}

Luciano F. La Sala
Consejo Nacional de Investigaciones Cient?ficas y T?cnicas (CONICET)
C?tedra de Epidemiolog?a
Departamento de Biolog?a, Bioqu?mica y Farmacia
Universidad Nacional del Sur
San Juan 670
Bah?a Blanca (8000)
Argentina