[edNorth]

eduardo : Yes, Stab.V/KG 25 did exist, eventually (1944)!
I have seen that in records, and it had F (1945).

However there are two versions of code letters out, the other:

The New Luftwaffe Unit Codes

These appear first in March 1939 but were finalized in an order 04.07.1939. The new unit code system was simpler than the old (but had more letters than often reported). It was as follows: The first two letters denoted Geschwader, Gruppe, Staffel or independent unit, the third was individual machine letter (and regularily painted in Staffel or Stab. colour). The fourth denoted basically Stab. or Staffel. The six Stab. indentification letters were (basically):

A - Geschwader Stab. (Green)
B - Stab. I Gruppe (Green)
C - Stab. II Gruppe (Green)
D - Stab. III Gruppe (Green)
F - Stab. IV Gruppe (Green)
G - Stab. V Gruppe (Green)

Other sources state the letter “F” was for V Gruppen as Stabstaffel/KG 26 was known as V/KG 26 before!
Often the fourth letter was painted Black (1H+BF) where the individual letter (here B) was Bright-Green. Late in the war the fourth letter was often used as an special single-Staffeln designator. In this example the unit (KG 26) was apparently using an Stabstaffel of eight Ju 88 A-4 (Radar-equipped) ex-Bombers for Long-Range Reconnaissence or Long-Range Radio homing from October 1944 to May 1945. Others code letters (such as A3+AE) were used as Training codes for KG 200 (the Special Secret Unit) and use of “E” is also known in other instances.

Staffeln / Gruppe indentification letters:

Colour I Gr II Gr III Gr IV Gr V Gr
-------------------------------------------
White 1 H 4 M 7 R 10 U 13 X
Red 2 K 5 N 8 S 11 V 14 Y
Yellow 3 L 6 P 9 T 12 W 15 Z

( 16 Q, 17 J, 18 O, 19 E and 20 I )

If an fourth or fifth Staffeln was added to any Gruppe the colour was Blue and Black respectively. Known use of 16. and 17. Staffel was with KG 40 (Heinkel He 177) but there may have been others. In the early years of the war the Staffel letter U was used for the Training Staffel or Kette (four aircraft) and in some rare cases the fourth letter was omitted altogether.

- Open for debate... Ed