The spreadsheet is the main part of LabPlot when working with data and consists out of columns. Column is the basic data set in LabPlot used for plotting and data analysis. Every column of the spreadsheet is specified by its name and the type - numeric, text, month names, day names and date and time. Also, for each type different representation formats can be assigned like decimal or scientific format for numeric columns etc.
In addition to these properties it is also possible to specify the plot designation - LabPlot is using this property in some places to to automatically recognize how to plot the data and which columns to use as X, Y, etc.
Data Analysis and Visualization
Sometimes it is required to ignore some data points in the visualization or when performing some data analysis like fitting etc. To exclude some data points from plotting and data analysis without deleting them, masking of those data points can be used. You can mask the selected data points in the spreadsheet (Selection/Mask Selection from the spreadsheet cell context menu).
In the example below a fit was performed to the original data was performed containing some obvious measurement errors and a fit where those outliers were masked. TODO: screenshot with two fits