References CDC          Reference tables from CDC 2000
References NL3          Reference tables from Third Dutch Growth Study
                        1980
References NL4          Reference tables from Fourth Dutch Growth Study
                        1997
References WHO          References WHO
ageGrid                 Creates an age grid according to a specified
                        format.
boys7482                Growth of Dutch boys
extractLMS              Extracts LMS values from a gamlss object.
wp.twin                 Superposes two worm plots
y2z                     Converts measurements to standard deviation
                        scores (SDS)
z2y                     Convert standard deviation scores (SDS) to
                        measurements
