Times given in reports -- across the International Date Line

In after action reports for the Pacific Theater, I find the time is often followed by a capital "I" and in some cases the the word "Item". For example, 4 pm on March 31st near Okinawa is written: 311600 I

What does the "I" stand for?

 

The time zone. ITEM is UTC+9.

 

One! J, which indicates "local time" if
ZULU Time is Greenwich or 0.
Running East it is:
+1 - A
+2 - B
+3 - C
+4 - D
+5 - E
+6 - F
+7 - G
+8 - H
+9 - I
+10 - K
+11 - L
+12 - M - AKA the International Date Line

Running West it is:
-1 - N
-2 - O
-3 - P
-4 - Q
-5 - R
-6 - S
-7 - T
-8 - U
-9 - V
-10 - W
-11 - X
-12 - Y - AKA the International Date Line again

 

Thanks. Is "ITEM" official terminology or jargon for India Time Zone?

 

ITEM is the World War II standard phonetic alphabet for the letter "I".

In the modern NATO STANAG it is INDIA.

See: WWII Phonetic Alphabet | Saco