Selection of clusters on the number of stars

With the usual options -gt, -lt, -i, one may perform selections of clusters according to the number of stars for which data are available. This is useful to know which clusters may be used for some study, or which should be observed.

Clusters with no data are not recorded, except for ubv and mk data types.

Please, respect the syntax:

slm data-type option limit

Examples:

slm vsn -gt 30
selects clusters that have more than 30 stars observed for Vsini
slm ubv -i 5 10
selects clusters that have between 5 and 10 stars observed photoelectrically in UBV