How to decode the hand-written markings on wartime aerial photos from WW2?

The aerial photos taken by American planes flying over Japanese-occupied Hong Kong in WW2 have a set of markings written across the top of the negatives. You can see several examples above. What do the different markings mean?

Craig Mitchell of Project Avenger mentioned this to his contacts in the U.S. military veteran community in Hong Kong, and they generously investigated. Here are their findings:


Regarding your question about WWII photo reconnaissance markings, below is our best guess based on internet sleuthing, our prior military experience, and what was typically written on negatives at that time.  We're least confident about the italicized markings.
 
Marking
Meaning
Details
↑N Orientation Rotate the photo so the arrow points upwards (north) to align the photo.
21PR
Unit
5MB5
Mission ID?
Maybe 5th mission for "MB5" series?
LV36
Camera/View
Left Vertical, Frame 36.
2:1:1240
Date & Time
February 1st at 12:40 PM
24
Focal length
24-inch lens
30500A
Altitude
30,500 feet.
SL.ME
Task Type?
Maybe "Shipping List - Military Establishments?" 
2218N11411
Coordinates
22°18'N, 114°11'E. 
HONG KONG DOCKS Items of interest  

We’re still scratching our heads over the "SL.ME" marking.  Given the deep bench of history buffs that frequent your site, we’d be very curious to see if any of your readers have a better answer on what that stands for.

Date picture taken
1945