If your waveform contains large number of data points, entering them manually can clutter the schematic. LTspice allows importing waveform data from a text file.
The file name is specified in the PWL statement:
Example syntax
PWL REPEAT FOREVER FILE=data.txt ENDREPEAT
Figure 7 shows the text file and resulting waveform using an example of an imported waveform that repeats indefinitely.
See the LTspice manual for more information about importing waveform data, including FILE, SCOPEDATA, and WAVEFILE import syntax.
It keeps the LTspice schematic clean and manageable while enabling complex waveform simulations.
Related Articles:
What is LTspice?
An Introduction to LTSpice
What is a Piecewise Linear (PWL) function in LTspice and when it should be used?
How can you repeat PWL waveform in LTspice?