IDENT: Package for identification in behavioural setting. The IDENT package solves identification problems with no a priori separation of the variables into inputs and outputs and representation invariant approximation criterion. The model class consists of linear time-invariant systems of bounded complexity and the approximation criterion is the minimum of a weighted 2-norm distance between the given time series and a time series that is consistent with the model. The problem is equivalent to and is solved as a mosaic-Hankel structured low-rank approximation problem.Additional nonstandard features of the software are specification of exact and missing variables and identification from multiple experiments.