Notation in atomic structure

In the book, *The theory of atomic structure and spectra*, Robert D. Cowan says that the allowed terms of $p^2$ are $^1S$, $^1D$, $^3P$ and so the possible terms of $p^2 + p\quad$ (obtained by using the vector model) are:


$$^2P^\circ,\quad ^2P^\circ D^\circ F^\circ,\quad ^{2,4}S^\circ P^\circ D^\circ 
 \tag1$$ 


I am having trouble in understand the notation in $(1)$. For example the term $^2P^\circ$ means that $s=1/2,l=1$ and $^\circ$ means odd parity, but for the term $^{2,4}S^\circ P^\circ D^\circ$, I do not know what it means. Can anyone explain me it please?




Copied table below from "Quantum chemistry", Donald A. McQuarrie, University Science Books, 2008, [page 472](https://www.google.com/books/edition/Quantum_Chemistry/zzxLTIljQB4C?hl=en&gbpv=1&dq=%22term+symbols%22+%22equivalent+electrons%22&pg=PA472&printsec=frontcover)


This illustrates the notion that $p^2$ and $p^4$ are equivalent. 


[![enter image description here](https://i.stack.imgur.com/53BRe.png)](https://i.stack.imgur.com/53BRe.png)


I think the 2,4 superscript in Cowan's book for $^{2,4}S^\circ P^\circ D^\circ$ is a peculiar notation of his. Most other books seem to presume the reader knows the equivalency. 


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