I am trying to understand how maple "isprime" algorithm works. But I can't find anywhere what **special_primes** means.

showstat(isprime);

isprime := proc(n)

local btor, nr, p, r;

1 if not type(n,'integer') then

2 if type(n,('complex')('numeric')) then

3 error "argument must be an integer"

else

4 return 'isprime(n)'

end if

end if;

5 if n < 2 then

6 return false

elif **member(n,isprime:-special_primes)** then

7 return true

elif igcd(2305567963945518424753102147331756070,n) <> 1 then

8 return false

elif n < 10201 then

9 return true

elif igcd(8496969489233418110532339909187349965926062586648932736611545426342203893270769390909069477309509137509786917118668028861499333825097682386722983737962963066757674131126736578936440788157186969893730633113066478620448624949257324022627395437363639038752608166758661255956834630697220447512298848222228550062683786342519960225996301315945644470064720696621750477244528915927867113,n) <> 1 then

10 return false

elif n < 1018081 then

11 return true

else

12 r := gmp_isprime(n);

13 if not r or n <= 5000000000 then

14 return r

end if;

15 nr := igcd(408410100000,n-1);

16 nr := igcd(nr^5,n-1);

17 r := iquo(n-1,nr);

18 btor := modp(('power')(2,r),n);

19 if cyclotest(n,btor,2,r) = false or irem(nr,3) = 0 and cyclotest(n,btor,3,r) = false or irem(nr,5) = 0 and cyclotest(n,btor,5,r) = false or irem(nr,7) = 0 and cyclotest(n,btor,7,r) = false then

20 return false

end if;

21 if isqrt(n)^2 = n then

22 return false

end if;

23 for p from 3 while numtheory:-jacobi(p^2-4,n) <> -1 do

24 NULL

end do;

25 return evalb(TraceModQF(p,n+1,n) = [2, p])

end if

end proc