Net" wizard. Bidirectional - "Rectangle with triangle on two ends" around the text. This is chosen by the "Port Type" field in the "Label Net" wizard. File format Many of the LTspice files are stored as an ASCII text file, which can be viewed or edited with any ASCII text editor programs. One of the side benefits of an ASCII file format is that a schematic can be listed in a printed document / book / magazine / datasheet / research paper / homework assignment, which allows the reader to recreate LTspice files without electronic file distribution. LTspice filename extensions: .asc - schematic. It consists of a netlist based on SPICE text-based commands. .asy - electronic symbol shown in a schematic. .cir - external netlist input. .fft - FFT binary output. .lib - model library subcircuits. .plt - waveform viewer plot settings. .raw - binary output, optional ASCII output. .sub - subcircuit. .lib / .sub / .mod / .model - device model. While any file extension is allowed, users tend to gravitate towards common ones. Example The following example can be viewed by copying each into two different text files. For each, copy the text in the gray box from this article, paste into an ASCII text editor, saving as a text file. Both files must have the same "base name" and sit in the same directory. To see it, opening the "asc" file with LTspice then click the "Run" button inside LTspice software. LTspice_RC.asc LTspice_RC.plt Schematic file LTspice schematics are stored as an ASCII text file with a filename extension of "asc". The following example shows the contents from a small LTspice schematic file for a simple RC circuit with four schematic symbols: V1 is 10 volt DC voltage source, R1 is 1K ohm resistor, C1 is 1 uF capacitor, ground. The bottom three TEXT lines are: 1) a transient simulation directive with a stop time parameter of 10 ms (.tran 10mS), 2) a SPICE directive to set the initial condition of RC "out" net to zero volts (.ic v(OUT)=0V), and 3) a text comment (title). Version 4 SHEET 1 880 680 WIRE 224 96 128 96 WIRE 128 160 128 96 WIRE 224 192 224 176 WIRE 288 192 224 192 WIRE 224 208 224 192 WIRE 128 288 128 240 WIRE 224 288 224 272 WIRE 224 288 128 288 WIRE 224 304 224 288 FLAG 224