Complete documentation of each processing step
Basically all data need to be processed and analysed in one way or other to get insight and draw conclusions. Full reproducibility, hence, requires a gap-less record of each and every processing and analysis step starting with the raw data and ending with the published figure or table.
With most data nowadays obtained digitally, the amount of data is growing exponentially as well, rendering manual tracing of processing and analysis steps nearly hopeless. Therefore, a system that automatically saves the metadata of each processing and analysis step seems to be the only choice.
These metadata need to include references to the exact version(s) of the routines and the operating system used, as well as a complete set of parameters for each processing and analysis step. The latter needs to include implicit parameters as well, as they may change over time. Impliicit parameteres refer here to parameters usually set to (default) values within the routine, not requiring explicit user input.
For details on versioning of routines, see the respective requirements section on versioning.