In reply to Mr. Lee:
The Nordic grades have very clear equals in the French system, before 8a it is sometimes with slash grades, sometimes not
Here's the truth:
7- = 6b
7-/7 = 6b+
7 = 6c
7/7+ = 6c+
7+ = 7a
7+/8- = 7a+
8- = 7b
8 = 7b+
8/8+ = 7c
8+ = 7c+
9- = 8a
So 8-/8 and 8+/9- do not have a direct equivalent without using a slash in the French grades.
From 9- upwards you add a slash grade everytime you go up a French grade, so 9-/9 is 8a+, 9 is 8b, 9/9+ is 8b+ etc.