Akp needs to know that The Visual, The Center y The Face of group are 3 very DIFFERENT POSITIONS in groups

e.g.

in snsd; YOONA is Visual of group, Center of group and also Face of group.

in exo-k; LUHAN was Visual of group, his successor is SEHUN. ...while KAI is center and face of group.

in f(x): SULLI was Visual of group , her successor is KRYSTAL. but KRYSTAL is/was also center and face of group.

in super junior; SIWON is Visual of group, DONGHAE is center and face of group.

in the grace: LINA was Visual of group, STEPHANIE was center of group

Disagree with some 'names' of that list. I'm ONLY AGREE with YoonA, Siwon, Minho, Lina and some more as the TRUE OFFICIAL VISUALS of their respective groups. The rest are center or face or just members of their groups, no true official visuals.
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There is ONLY 1 visual, ONLY 1 center and ONLY 1 face for each group, there are exceptions such as fx and exo where the official visuals left their groups so another member will take their positions as official visual of group.
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Let's check 5 SM kpop groups: Who is Visual? who is Center and who is Face of each group?
1.
snsd VISUAL is only YOONA, she is also Nation Visual, The Queen Visual of All the Visuals.
snsd CENTER is only YOONA, she is also Nation Center, The Queen Center of All the Centers
snsd FACE is only YOONA, she is also Nation's Fce, The Queen Face of all The faces of kpop groups
2.
suju VISUAL is only SIWON
suju CENTER is only DONGHAE
suju FACE is only DONGHAE
3.
shinee VISUAL is only MINHO
shinee CENTER is only TAEMIN
shinee FACE was JONGHYUN, he passed away, RIP. Now is TAEMIN
4.
fx VISUAL was SULLI (ot5), then sulli left fx. Now is KRYSTAL
fx CENTER was only KRYSTAL
fx FACE was only KRYSTAL
5.
exo-k VISUAL was LUHAN (OT12), luhan left exo. Now is SEHUN
exo-k CENTER is only KAI
exo-k FACE is KAI
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Nice day to everyone