Table of Contents - 11.1.3. Standard basis (unit vectors)

According to Wikipedia ("Standard basis", 16-Mar-2019,
https://en.wikipedia.org/wiki/Standard_basis) "In mathematics, the standard
basis (also called natural basis) for a Euclidean space is the set of unit
vectors pointing in the direction of the axes of a Cartesian coordinate
system.", and ("Unit vector", 16-Mar-2019,
https://en.wikipedia.org/wiki/Unit_vector) "In mathematics, a unit vector in
a normed vector space is a vector (often a spatial vector) of length 1.".
In the following, the term "unit vector" (or more specific "basic unit vector")
is used for the (special) unit vectors forming the standard basis of free
modules. However, the length of the unit vectors is not considered here, so it
is not required to regard normed spaces.