In most graphing / visualisation packages, a single dataset (XY data, curve, trace, line - call it what you will) exists independently of the others. In uChroma a number of datasets are grouped together into a collection. The individual datasets may still be displayed as individual line plots, or may be used to generate a continuous surface (see collection styling) but they are all displayed at the same time as each other. In some sense this complicates the use of uChroma as a 2D graphing package, but permits the facile creation of 3D dataset and the interrogation thereof.
Multiple collections can exist simultaneously in a single session, and each collection may contain sub-collections in the form of fitted or extracted data. All collections in the current session can be viewed through the collections list.