2.1.6 [SVG1.1:2011] Section 10.7.3, Glyph orientation within a text run
In some cases, it is required to alter the orientation of a sequence of characters relative to the inline-progression-direction. The requirement is particularly applicable to vertical layouts of East Asian documents, where sometimes narrow-cell Latin text is to be displayed horizontally and other times vertically. Two properties control the glyph orientation relative to the reference orientation for each of the two possible inline-progression-directions. 'glyph-orientation-vertical' controls glyph orientation when the inline-progression-direction is vertical. 'glyph-orientation-horizontal' controls glyph orientation when the inline-progression-direction is horizontal.
IE9 Mode, IE10 Mode, IE11 Mode, and EdgeHTML Mode (All Versions)
The glyph-orientation-horizontal and glyph-orientation-vertical attributes are not supported.