# Lowercase phi (φ) seemingly used for diameter in diagram instead of Ø?

On a technical drawing for resistors, the lead diameter was given as $$\varphi 0.55\text{mm}$$. Since they also specify the wire is 24 SWG, and 24 SWG is a diameter of 0.559mm, did they simply use φ (phi) when they should have used Ø, or is this actually accepted notation? And if it is accepted usage, does the usage of φ differ from Ø?

• A picture would speak a thousand words.... – user16 Jan 12 '19 at 1:33
• @GlenH7 Wish I had one I could share (NDA). I can tell you the "drawing" in question was nothing more than an orthographic projection of a through-hole (PTH) resistor with "φ0.55mm" in vague proximity to the end of the lead with no other markings. I only figured out it referenced the diameter because elsewhere in the textual spec it said the leads were 24 SWG, which I know has a diameter of 0.559mm. – type_outcast Jan 12 '19 at 13:30