GDL direction slab, Unicorn Ridge [????- ] | Gwulo: Old Hong Kong

GDL direction slab, Unicorn Ridge [????- ]

Current condition: 
Ruin

Year completed is: Accurate
Condition at last visit: Top face complete, all directions visible
Date of last visit:
Ref: ROB-01013
Other:

Text on slab:

L 59
Bn HQ
L 70 - 75 PB 219 - 222

Comments

22.35691  114.19275

 

L60 70 TO 75 PB219 TO 222

IL59

Bn HQ

What does "I" stand for before L59?

GDL direction slab Unicorn Ridge
GDL direction slab Unicorn Ridge, by ck89

Position adjusted to your co-ordinates thanks. Unfortunately, I have no idea what the I represents.