Basic arithmetic on NMdata objects
An object that is not of class 'NMdata'.
When 'dimnames', 'merge', 'cbind', 'rbind', or 't' is called on an 'NMdata' object, the 'NMdata' class is dropped, and then the operation is performed. So if and 'NMdata' object inherits from 'data.frame' and no other classes (which is default), these operations will be performed using the 'data.frame' methods. But for example, if you use 'as.fun' to get a 'data.table' or 'tbl', their respective methods are used instead.