Number recognition in table is too eager

[Mc-Zen]

In general, Zero is a bit too eager recognizing the content of a cell as a number. While non-text content is (as intended) never interpreted as a number, plain text usually is.

For example [Text] becomes $T\times 10^\mathrm{xt}$ because Zero does not actually check if the individual characters are really digits.

However, this is also not quite unintended because numbers can actually contain letters - a common case are hexadecimal numbers. Also, it might be useful for some applications to allow a symbolic exponent, e.g., num[1.23ex] which is rendered as $1.23\times 10^x$.