Controlling the size(height) stacked fraction when place in MicroStation Word Processor using true type fonts can be a challenge
The size of the stacked fraction is often larger than rest of text being placed. When TrueType elements there is a special stacked fraction representation where MicroStation manually draws multiple characters and lines to make something look like a fraction which are measured differently than normal glyphs. This can affect linespacing when placing multi-line text where the linespacing value is not consistent between text lines when text is placed. This issue does not occur when using Bentley fonts as there are designated character for most fractions.
http://communities.bentley.com/products/microstation/w/microstation__wiki/configuration-variables-in-microstation-v8