Plot Pro is a scientific 2D plotting program. The project started in 1993 with SciPlot on NeXTStep and continues with "Plot" for OS X till 2007.
Plot is designed for everyday plotting: it is easy to use, it creates high quality plots, and it allows easy and powerful manipulations and calculations of data.
Basically Plot allows you to work with multiple documents where every document consists of one or more XY data sets (called buffer in Plot). There is also the ability to add subviews (plots inside plots) to your document. A subview is completely independent with its own data buffers, graphic attributes, etc.