\begin{definition}[Definition:General Logarithm/Common/Notation for Negative Logarithm]
Let $n \in \R$ be a real number such that $0 < n < 1$.
Let $n$ be presented (possibly approximated) in scientific notation as:
:$a \times 10^{-d}$
where $d \in \Z_{>0}$ is a (strictly) positive integer.
Let $\log_{10} n$ denote the common logarithm of $n$.
Then it is the standard convention to express $\log_{10} n$ in the form:
:$\log_{10} n = \overline d \cdotp m$
where $m := \log_{10} a$ is the mantissa of $\log_{10} n$.
\end{definition}