How recently did SS write in Potions book?

[Constance Vigilance]

No: HPFGUIDX 141700

> ~aussie~
"Alledgedly" made something click with me. There are inconsistancies 
> in the potions book with teen Snape.
> 
> - Why call himself a Half-Blood while in Slytherin?
> 
> - Who could he practise the "sectumsempra" curse on while a student 
> without getting expelled. (Remember, McGoonagall heard what Harry 
> did to Draco, yet didn't recognise the injuries from Snape's years 
> at school. Both she and Mdm. Pomfrey were at Hogwarts then and would 
> have remebered Snape for inventing something that causes such wounds)
> 

CV: Apparently not. Teen!Snape used sectupsempra on James.

Snape's Worst Memory (p 647, US ed.)

"Bad luck, Prongs," said Sirius briskly, turning back to Snape. "OY!"

But too late; Snape had directed his wand straight at James; there was 
a flash of light and a gash appeared on the side of James's face, 
splattering his robes with blood.

CV