Taka-sa means 'height'; it is a noun derived from the adjective takai 'high, tall'.
Normally taka-sa is written , with the suffix -sa written in hiragana, as below:
However, there is also a rather peculiar quasi-technical usage, found when writing dimensions, in which the suffix -sa is written in katakana (). The sign below was right next to the sign found above.
A Google search in August 2003 found that takasa was overwhelmingly written . Only in a small minority of cases was found.