Kind of a round about way to do it using stacked balloons. Someone on the SW Forum suggested using blocks.
Click on stacked balloons.
Insert (2) balloons. Click out.
Click back in the 1st balloon.
Change balloon to text.
Open Character map.
Go to ISOCTEUR. 3rd row from bottom - 3rd from right. Right Angle (U+221F).
Copy & Paste symbol onto the Balloon Text line.
Go to More Properties.
Change border to none.
Change arrow to bent leader.
Click out.
Click on 2nd balloon.
Change to text and add 4 spaces before adding your edge requirement.
More Properties - Border, None.
Click on Right Angle - More Properties.
Uncheck - Use Doc Font.
Change font size to (?28)
Click out.
Click on edge dimension. - More Properties.
Uncheck - Use Doc Font.
Height - Units - Space (.15)
You can use favorites to get the right angle symbol on the 1st. balloon.
If you have difficulty hi-lighting the 2nd. balloon, right click & Select Other.
Sylvia