[mdspan.layout.general]

(1.1)
M denotes a layout mapping class.
(1.2)
m denotes a (possibly const) value of type M.
(1.3)
i and j are packs of (possibly const) integers that are multidimensional indices in m.extents() ([mdspan.overview]).

[Note 1:
The type of each element of the packs can be a different integer type.
— end note]
(1.4)
r is a (possibly const) rank index of typename M::extents_type.
(1.5)
$d_{r}$ is a pack of (possibly const) integers for which sizeof...( $d_{r}$ ) == M::extents_type::rank() is true, the $r^{th}$ element is equal to 1, and all other elements are equal to 0.

(2.1)
Let is-mapping-of be the exposition-only variable template defined as follows: template<class Layout, class Mapping> constexpr bool is-mapping-of = // exposition only is_same_v<typename Layout::template mapping<typename Mapping::extents_type>, Mapping>;
(2.2)
Let is-layout-left-padded-mapping-of be the exposition-only variable template defined as follows: template<class Mapping> constexpr bool is-layout-left-padded-mapping-of = see below; // exposition only where is-layout-left-padded-mapping-of<Mapping> is true if and only if Mapping denotes a specialization of layout_left_padded<S>::mapping for some value S of type size_t.
(2.3)
Let is-layout-right-padded-mapping-of be the exposition-only variable template defined as follows: template<class Mapping> constexpr bool is-layout-right-padded-mapping-of = see below; // exposition only where is-layout-right-padded-mapping-of<Mapping> is true if and only if Mapping denotes a specialization of layout_right_padded<S>::mapping for some value S of type size_t.
(2.4)
For nonnegative integers x and y, let $LEAST-MULTIPLE-AT-LEAST (x, y)$ denote
- (2.4.1)
  y if x is zero,
- (2.4.2)
  otherwise, the least multiple of x that is greater than or equal to y.

23 Containers library [containers]