There are more signs in this type of glyph then what at a first glance seems to be the case. Subtle differences appear when glyphs are compared. Therefore it is necessary to define what is an unmarked glyph. Furthermore, what is an unmarked glyph is different in different rongorongo texts.

What here at first follows below is a preliminary attempt at defining what constitutes an unmarked GD11 type of glyph (blue glyph labels) in different rongorongo texts.

Tahua

Aa3-1	Aa3-5	Aa4-74	Aa5-16	Aa5-29	Aa5-74	Aa6-59	Aa8-6
unmarked					big	narrow
Ab1-50	Ab1-61	Ab1-76	Ab2-30	Ab2-72	Ab3-27	Ab5-33	Ab6-19
right wing close to body			unmarked		left wing short
					left foot somewhat longer	right foot longer
					ordinary hook on the beak		big hook on the beak
				Presumably these different signs mean different things. To convince yourself of this possibility, compare with the glyphs for Matariki i nika and Matariki i raro in Tahua. Big hook and left foot longer might mean the moon.
Ab6-30	Ab7-35	Ab8-31	Ab8-34
left wing short and big hook on the beak
both feet long	left foot longer	right foot somewhat longer
right wing close to body	right wing not close to body

Aruku Kurenga

Ba2-8	Ba2-12	Ba2-17	Ba7-2	Ba8-42	Ba9-11	Ba10-7	Ba10-9
nearly symmetrical feet			unmarked	right foot longer	unmarked
						Differences in size (e.g. Ba2-8 and Ba10-9) are here due to my procedures for copying glyphs.
Ba10-16	Bb1-7	Bb1-18	Bb1-26	Bb4-16	Bb6-19
unmarked				nearly symmetrical feet	unmarked

Small Santiago

						The strange head is certainly a sign. What determines an unmarked glyph is not a 'majority rule'; here the marked glyphs are twice as many as the unmarked.
Ga3-8	Gb4-15	Gb8-18	Gb8-22	Gb8-23	Gb8-25
unmarked		right foot longer, also strange head form

Large Santiago

Ha2-2	Ha2-52	Ha4-46	Ha7-126	Ha8-107	Ha8-109	Ha8-110	Ha9-111
long feet		short feet	unmarked
Ha11-103	Ha12-11	Hb1-221	Hb2-1	Hb2-3	Hb2-12	Hb4-4	Hb5-7
unmarked
							Large Santiago often has quite standardized glyphs without signs.
Hb8-116	Hb8-139	Hb9-20	Hb9-47	Hb9-58	Hb10-12	Hb12-36
unmarked	long feet	unmarked

Large St Petersburg

Pa4-9	Pa4-28	Pa4-30	Pa7-11	Pa8-11	Pa10-8	Pa10-9	Pa10-15
short feet			well fed
eye		no eye
Pa11-25	Pb2-23	Pb2-25	Pb3-28	Pb4-13	Pb4-15	Pb6-2	Pb6-59
well fed	unmarked

Small St Petersburg

Qa3-14	Qa7-125	Qa9-17	Qb1-5	Qb1-11	Qb2-13	Qb3-10	Qb3-12
tiny wings, fishy feet	unmarked	straight left wing, strange head
		not thin long left wing			thin long left wing	not thin long left wing
		not big bird					big bird
				A B G H P Q sum unmarked 7 9 2 19 9 1 47 marked 13 5 4 4 7 11 44 sum 20 14 6 23 16 12 91 % marked 65 36 67 17 44 92 48
Qb4-14	Qb6-119	Qb6-122	Qb6-124
depressed beak, straight left wing, strange head	strange head

A table showing what perhaps are unmarked GD11 glyphs:

A	B	G	H	P	Q