The term "pop mark" has several meanings depending on the context. There's no single, universally accepted definition.
1. Pop Marks in Manufacturing and Engineering
In the context of manufacturing and engineering, specifically within CAD/CAM software like Tekla Structures, "pop marks" refer to marks indicating the location of punched or drilled holes in a workpiece. These marks are often created during NC (Numerical Control) programming to guide the manufacturing process. For example, the Tekla Structures documentation explains how to create these pop marks for export in NC files (https://support.tekla.com/doc/tekla-structures/2018i/int_nc_creating_pop-marks). They are crucial for accurate hole placement during fabrication. Converting contour lines in NC files to these punch marks is a common task in some software (https://forums.autodesk.com/t5/advance-steel-forum/convert-contour-lines-in-nc-files-to-pop-marks-punch-marks/td-p/1177096).
2. Pop Marks (Pockmarks) as Skin Blemishes
In the medical context, "pop mark" can informally refer to a pockmark, which is a concave blemish or scar on the skin. These are often caused by acne or smallpox and appear as small holes or indentations (https://www.merriam-webster.com/dictionary/pockmark). They're also sometimes called pick marks ([Reference 1]).
3. Pop Marks as Nicknames or Informal Terms
"Pop" can be a colloquial term for "father", so "Pop Marks" might also refer to a person's name, such as in an obituary (https://www.whitleymemorialfuneralhome.com/obituaries/obituary-listings?obId=32868907).
4. Pop Marks in Email (POP)
In the context of email, "pop marks" isn't a standard term. However, the term "POP" refers to the Post Office Protocol, an email retrieval method. When using POP, messages are typically downloaded from the server to the local email client, and this download might implicitly mark messages as read on the server, depending on the client and server settings (https://support.google.com/a/answer/6089246?hl=en, https://answers.microsoft.com/en-us/outlook_com/forum/all/outlook-marks-my-pop-exchange-messages-as-read-on/9a7391f0-2651-4305-b7ec-3e92e6b3d094). This isn't a "mark" in the same sense as the other meanings above.
