9.visual_mode

" three sub mode
    v           active char visual
    V/shift+v   active line visual
    Ctrl+v      active chunk visual

" visual operator
    gv          reselect last hlselect
    o           swich selection boundary

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vi{             select content in {
.               repeate last oprator
vit             select content in tag 
U/u             Upper/lower
r               replace selection. then tap ESC effect on multi line
c               delete and insert. then tap ESC effect on multi line
Ctrl+v          rect selection. then tap $ include extent chars. then tap A append end. then tap ESC effect on multi line