Printed matter (text, symbols, images) usually falls under copyright law and not patent law. The exception — when the printed matter improves a product’s functionality.
Nonfunctional printed matter does not distinguish claimed product from an otherwise identical prior art productMPEP 2112.01 (and various court cases)
There is one key difference between patents and copyrights. For previously known devices that have human readable printed material, ask: is the only new thing the printed material itself? Is the printed material otherwise “nonfunctional?” If so, as a rule of thumb, don’t file a patent, file a copyright instead.
This simple rule is sometimes not so simple in practice. The catch is, what is “functional”, and what is “non-functional?”
Functional vs. nonfunctional (MPEP 2111.05):
Unfortunately, the legal definition of “functional” is circular. “Functional printed matter is functional”. The underlying examples are based on case law. Results can vary. For example, the Federal Circuit has determined that measuring marks on measuring cups are functional. The Federal Circuit has also determined that radio-opaque markings on implantable medical devices are nonfunctional. This, even though the markings can prevent harm or death!
So yeah, results can vary. In any event, the device (or method) better be novel. You also need to have arguments about how the markings improve the function of the underlying device.
The rules can change if the printed matter controls the operation of a machine (e.g., computer-readable medium.) If the computer-readable medium causes the device or method to act differently, it is usually considered functional. (Here “differently” can mean adding or subtracting data.) But if the operation only transmits messages to humans, it is generally classified as nonfunctional.
The above rules, although a bit fuzzy at times, at least have a legitimate purpose. They tell you if you should be sending your work to the USPTO or the US Copyright office.
“Alice” (35 USC 101) issues can pile ambiguity on ambiguity
The Alice “abstract” rules are unclear and tend to use medieval logic. Be aware that occasionally, the USPTO (or the courts) may use the ambiguity surrounding the “functionality” of a given set of printed material against you. They may argue that your printed material is “nonfunctional” and thus renders your patent’s claims “abstract.”
So if you are filing a patent, try to avoid printed material claim limitations whenever possible. If you must use them, try to provide a lot of evidence that supports functionality.