(Edited to upload the image to imgur and avoid spammy advertisements). Here I'll date myself: I remember this as "diode with a gate". Back when we did circuit

(Edited to upload the image to imgur and avoid spammy advertisements). Here I'll date myself: I remember this as "diode with a gate". Back when we did circuit diagrams with stencils, you had the diode stencil which looks like a triangle with a line on top, and then with the electrical stencils you had "decorations". The intention was to put down the original symbol on the paper, move the decorations stencil over top of it and then add the required decorations. It's why diode symbols look like this: https://imgur.com/a/0tSLV7O https://imgur.com/a/0tSLV7O (notice "step recovery diode"). The "lightning bolt" isn't a lightning bolt, it's a hint that this diode is going to have a very sharp "snap off" in the waveform. See: https://www.electronics-notes.com/articles/electronic_components/diode/step-recovery-diode-srd.php https://www.electronics-notes.com/articles/electronic_compon... OK so why do we have a seperate decorator for a diode? Can't we just have a pocket full of stencils for diodes? Space was at a premium back then. It goes back to daisy wheels and typeballs: https://en.wikipedia.org/wiki/Printer_(computing)#Impact_printers https://en.wikipedia.org/wiki/Printer_(computing)#Impact_pri... You would have one position for "diode" and one position for "decorator" and the printer would know when it got one ASCII char it would print the diode, then send whatever the thin space is to advance the print carriage a small step, then print the decorator. Someone should be able to find a daisy wheel or typeball dedicated to circuits and bear this out.