A similar question on s-shaped quotation marks in another philosophy book came up on Graphic Design and let me do some research.
In particular, I stumbled upon Metaphysics, Mathematics, and Meaning by Nathan Salmon which has entire passages about quotation marks and in particular states at one point:
I use Quine’s quasi-quotation marks, ‘⌜’ and ‘⌝’ in combination with ‘α’. In quasi-quotation, all internal expressions are quoted, i.e., mentioned (designated), except for metalinguistic variables, whose values are mentioned. I use single quotation marks for direct (expression) quotation. Following Kaplan, I use superscripted occurrences of ‘m’ as indirect-quotation marks, and superscripted occurrences of ‘M’ as indirect-quasi-quotation marks.
Taking all this together, I guess that it is quite common in philosophy to use different types of quotation marks to distinguish different forms of quotation or reference on a meta level such as (to give simple examples):
- Citing another author verbatim.
- Referring to the word as such (and not what it means).
- Scare quotes and indicating metaphoric use of a word (such as for lack of a better word).
- Referring to the meaning of a word.
- Marking a word or term that is being defined at that very point.
I still do not know, what these particular quotation marks mean, but I am pretty confident that they are a form of special-purpose notation that is only used by Carnap or at most in philosophy. Whatever their meaning is, Carnap should have introduced them at some point (or it should be common knowledge in the respective field), presumably in § 75 as that’s pretty much what he is writing in the passage in question:
More precisely in the terminology of § 75: ₚmeine Erlebnisse ͩ.