diff --git a/docs/api_reference/src/quantities.tex b/docs/api_reference/src/quantities.tex
index 2ee4305a4..5e77acf3a 100644
--- a/docs/api_reference/src/quantities.tex
+++ b/docs/api_reference/src/quantities.tex
@@ -48,8 +48,6 @@
 
 export namespace mp_units {
 
-enum class @\libglobal{text_encoding}@ : std::int8_t { utf8, portable, default_encoding = utf8 };
-
 enum class @\libglobal{quantity_character}@ { scalar, complex, vector, tensor };
 
 // \ref{qty.helpers}, helpers
@@ -95,7 +93,12 @@
 
 namespace mp_units {
 
-// \ref{qty.symbol.text}, class template \exposid{symbol-text}
+// \ref{qty.sym.txt}, class template \exposid{symbol-text}
+
+enum class @\libglobal{text_encoding}@ : std::int8_t { utf8, portable, default_encoding = utf8 };
+
+template<std::size_t N, std::size_t M>
+class @\exposidnc{symbol-text}@;  // \expos
 
 // \ref{qty.expr.temp}, expression template
 
@@ -120,7 +123,7 @@
 
 // \ref{qty.dim.types}, types
 
-template<symbol_text Symbol>
+template<@\exposidnc{symbol-text}@ Symbol>
 struct base_dimension;
 
 template<typename... Expr>
@@ -227,7 +230,7 @@
 
 // \ref{qty.mag.types}, types
 
-template<symbol_text Symbol, long double Value>
+template<@\exposidnc{symbol-text}@ Symbol, long double Value>
   requires(Value > 0)
 struct mag_constant;
 
@@ -286,39 +289,39 @@
   requires @\seebelownc@
 struct scaled_unit;
 
-template<symbol_text Symbol, auto...>
+template<@\exposidnc{symbol-text}@ Symbol, auto...>
 struct named_unit;  // \notdef
 
-template<symbol_text Symbol, @\exposconceptnc{QuantityKindSpec}@ auto QS>
+template<@\exposidnc{symbol-text}@ Symbol, @\exposconceptnc{QuantityKindSpec}@ auto QS>
   requires @\seebelownc@
 struct named_unit<Symbol, QS>;
 
-template<symbol_text Symbol, @\exposconceptnc{QuantityKindSpec}@ auto QS, @\libconcept{PointOrigin}@ auto PO>
+template<@\exposidnc{symbol-text}@ Symbol, @\exposconceptnc{QuantityKindSpec}@ auto QS, @\libconcept{PointOrigin}@ auto PO>
   requires @\seebelownc@
 struct named_unit<Symbol, QS, PO>;
 
-template<symbol_text Symbol>
+template<@\exposidnc{symbol-text}@ Symbol>
   requires @\seebelownc@
 struct named_unit<Symbol>;
 
-template<symbol_text Symbol, @\libconcept{Unit}@ auto U>
+template<@\exposidnc{symbol-text}@ Symbol, @\libconcept{Unit}@ auto U>
   requires @\seebelownc@
 struct named_unit<Symbol, U>;
 
-template<symbol_text Symbol, @\libconcept{Unit}@ auto U, @\libconcept{PointOrigin}@ auto PO>
+template<@\exposidnc{symbol-text}@ Symbol, @\libconcept{Unit}@ auto U, @\libconcept{PointOrigin}@ auto PO>
   requires @\seebelownc@
 struct named_unit<Symbol, U, PO>;
 
-template<symbol_text Symbol, @\libconcept{AssociatedUnit}@ auto U, @\exposconceptnc{QuantityKindSpec}@ auto QS>
+template<@\exposidnc{symbol-text}@ Symbol, @\libconcept{AssociatedUnit}@ auto U, @\exposconceptnc{QuantityKindSpec}@ auto QS>
   requires @\seebelownc@
 struct named_unit<Symbol, U, QS>;
 
-template<symbol_text Symbol, @\libconcept{AssociatedUnit}@ auto U, @\exposconceptnc{QuantityKindSpec}@ auto QS,
+template<@\exposidnc{symbol-text}@ Symbol, @\libconcept{AssociatedUnit}@ auto U, @\exposconceptnc{QuantityKindSpec}@ auto QS,
          @\libconcept{PointOrigin}@ auto PO>
   requires @\seebelownc@
 struct named_unit<Symbol, U, QS, PO>;
 
-template<symbol_text Symbol, @\libconcept{Magnitude}@ auto M, @\libconcept{PrefixableUnit}@ auto U>
+template<@\exposidnc{symbol-text}@ Symbol, @\libconcept{Magnitude}@ auto M, @\libconcept{PrefixableUnit}@ auto U>
   requires @\seebelownc@
 struct prefixed_unit;
 
@@ -335,7 +338,7 @@
 } @\libglobal{percent}@;
 
 inline constexpr struct @\libglobal{per_mille}@ final :
-    named_unit<symbol_text{u8"\u2030" /* @\unicode{2030}{PER MILLE SIGN}@ */, "%o"},
+    named_unit<@\exposidnc{symbol-text}@{u8"\u2030" /* @\unicode{2030}{PER MILLE SIGN}@ */, "%o"},
                mag_ratio<1, 1000> * one> {
 } @\libglobal{per_mille}@;
 
@@ -1050,7 +1053,141 @@
 };
 \end{codeblock}
 
-\rSec2[qty.symbol.text]{Class template \exposid{symbol-text}}
+\rSec2[qty.sym.txt]{Class template \exposid{symbol-text}}
+
+\indexlibraryglobal{\exposid{symbol-text}}
+\begin{codeblock}
+namespace mp_units {
+
+template<std::size_t N, std::size_t M>
+class @\exposidnc{symbol-text}@ {  // \expos
+public:
+  @\exposidnc{fixed-u8string}@<N> @\exposidnc{utf8}@;    // \expos
+  @\exposidnc{fixed-string}@<M> @\exposidnc{portable}@;  // \expos
+
+  // constructors
+  constexpr explicit(false) @\exposidnc{symbol-text}@(char portable);
+  consteval explicit(false) @\exposidnc{symbol-text}@(const char (&portable)[N + 1]);
+  constexpr explicit(false) @\exposidnc{symbol-text}@(const fixed_string<N>& portable);
+  consteval @\exposidnc{symbol-text}@(const char8_t (&utf8)[N + 1], const char (&portable)[M + 1]);
+  constexpr @\exposidnc{symbol-text}@(const fixed_u8string<N>& utf8, const fixed_string<M>& portable);
+
+  // observers
+  constexpr const auto& utf8() const { return @\exposidnc{utf8}@; }
+  constexpr const auto& portable() const { return @\exposidnc{portable}@; }
+  constexpr bool empty() const { return utf8().empty(); }
+
+  // string operations
+  template<std::size_t N2, std::size_t M2>
+  friend constexpr @\exposidnc{symbol-text}@<N + N2, M + M2> operator+(const @\exposidnc{symbol-text}@& lhs,
+                                                         const @\exposidnc{symbol-text}@<N2, M2>& rhs);
+
+  // comparison
+  template<std::size_t N2, std::size_t M2>
+  friend constexpr auto operator<=>(const @\exposidnc{symbol-text}@& lhs,
+                                    const @\exposidnc{symbol-text}@<N2, M2>& rhs) noexcept;
+  template<std::size_t N2, std::size_t M2>
+  friend constexpr bool operator==(const @\exposidnc{symbol-text}@& lhs,
+                                   const @\exposidnc{symbol-text}@<N2, M2>& rhs) noexcept;
+};
+
+// deduction guides
+
+@\exposidnc{symbol-text}@(char) -> @\exposidnc{symbol-text}@<1, 1>;
+
+template<std::size_t N>
+@\exposidnc{symbol-text}@(const char (&)[N]) -> @\exposidnc{symbol-text}@<N - 1, N - 1>;
+
+template<std::size_t N>
+@\exposidnc{symbol-text}@(const fixed_string<N>&) -> @\exposidnc{symbol-text}@<N, N>;
+
+template<std::size_t N, std::size_t M>
+@\exposidnc{symbol-text}@(const char8_t (&)[N], const char (&)[M]) -> @\exposidnc{symbol-text}@<N - 1, M - 1>;
+
+template<std::size_t N, std::size_t M>
+@\exposidnc{symbol-text}@(const fixed_u8string<N>&, const fixed_string<M>&) -> @\exposidnc{symbol-text}@<N, M>;
+
+}
+\end{codeblock}
+
+\pnum
+\exposid{symbol-text} describes a symbol text.
+\exposid{utf8} stores its UTF-8 representation, and
+\exposid{portable} stores its portable representation.
+\tcode{\exposid{symbol-text}<N, M>} is a structural type\irefcppx{temp.param}{term.structural.type}.
+
+\pnum
+In the descriptions that follow,
+it is a \Fundescx{Precondition} that
+\begin{itemize}
+\item
+values of \tcode{char} are in the basic literal character set\irefcpp{lex.charset}, and
+\item
+for a parameter of the form \tcode{const \placeholdernc{CharT} (\&\placeholdernc{txt})[\placeholder{M}]},
+\tcode{(\placeholdernc{txt}[\placeholdernc{M} - 1] == \placeholdernc{CharT}())} is \tcode{true}.
+\end{itemize}
+
+\begin{itemdecl}
+constexpr explicit(false) @\exposidnc{symbol-text}@(char portable);
+consteval explicit(false) @\exposidnc{symbol-text}@(const char (&portable)[N + 1]);
+constexpr explicit(false) @\exposidnc{symbol-text}@(const fixed_string<N>& portable);
+consteval @\exposidnc{symbol-text}@(const char8_t (&utf8)[N + 1], const char (&portable)[M + 1]);
+constexpr @\exposidnc{symbol-text}@(const fixed_u8string<N>& utf8, const fixed_string<M>& portable);
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+Let \tcode{lhs} be \tcode{utf8} for the last two constructors,
+and otherwise:
+\begin{codeblock}
+std::bit_cast<@\exposidnc{fixed-u8string}@<N>>(@\exposidnc{basic-fixed-string}@(portable))
+\end{codeblock}
+
+\pnum
+\effects
+Equivalent to the \fakegrammarterm{mem-initializer-list}:
+\begin{codeblock}
+@\exposid{utf8}@{lhs}, @\exposidnc{portable}@{portable}
+\end{codeblock}
+\end{itemdescr}
+
+\begin{itemdecl}
+template<std::size_t N2, std::size_t M2>
+friend constexpr @\exposidnc{symbol-text}@<N + N2, M + M2> operator+(const @\exposidnc{symbol-text}@& lhs,
+                                                       const @\exposidnc{symbol-text}@<N2, M2>& rhs);
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+\effects
+Equivalent to:
+\begin{codeblock}
+return @\exposidnc{symbol-text}@<N + N2, M + M2>(lhs.utf8() + rhs.utf8(),
+                                   lhs.portable() + rhs.portable());
+\end{codeblock}
+\end{itemdescr}
+
+\begin{itemdecl}
+template<std::size_t N2, std::size_t M2>
+friend constexpr auto operator<=>(const @\exposidnc{symbol-text}@& lhs,
+                                  const @\exposidnc{symbol-text}@<N2, M2>& rhs) noexcept;
+template<std::size_t N2, std::size_t M2>
+friend constexpr bool operator==(const @\exposidnc{symbol-text}@& lhs,
+                                 const @\exposidnc{symbol-text}@<N2, M2>& rhs) noexcept;
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+Let \tcode{@} be the \fakegrammarterm{operator}.
+
+\pnum
+\effects
+Equivalent to:
+\begin{codeblock}
+return std::make_tuple(std::cref(lhs.utf8()), std::cref(lhs.portable())) @\atsign@
+       std::make_tuple(std::cref(rhs.utf8()), std::cref(rhs.portable()));
+\end{codeblock}
+\end{itemdescr}
 
 \rSec1[qty.expr.temp]{Expression template}
 
@@ -1384,7 +1521,7 @@
   }
 };
 
-template<symbol_text Symbol>
+template<@\exposidnc{symbol-text}@ Symbol>
 struct @\libglobal{base_dimension}@ : @\exposidnc{dimension-interface}@ {
   static constexpr auto @\exposidnc{symbol}@ = Symbol;  // \expos
 };
@@ -2057,7 +2194,7 @@
 \begin{codeblock}
 namespace mp_units {
 
-template<symbol_text Symbol, long double Value>
+template<@\exposidnc{symbol-text}@ Symbol, long double Value>
   requires(Value > 0)
 struct @\libglobal{mag_constant}@ {
   static constexpr auto @\exposidnc{symbol}@ = Symbol;       // \expos
@@ -2410,7 +2547,7 @@
 \begin{codeblock}
 namespace mp_units {
 
-template<symbol_text Symbol, @\exposconceptnc{QuantityKindSpec}@ auto QS>
+template<@\exposidnc{symbol-text}@ Symbol, @\exposconceptnc{QuantityKindSpec}@ auto QS>
   requires(!Symbol.empty()) && @\exposconceptnc{BaseDimension}@<std::remove_const_t<decltype(QS.dimension)>>
 struct @\libglobal{named_unit}@<Symbol, QS> : @\exposidnc{unit-interface}@ {
   using @\exposidnc{base-type}@ = named_unit;              // \expos
@@ -2418,7 +2555,7 @@
   static constexpr auto @\exposidnc{quantity-spec}@ = QS;  // \expos
 };
 
-template<symbol_text Symbol, @\exposconceptnc{QuantityKindSpec}@ auto QS, @\libconcept{PointOrigin}@ auto PO>
+template<@\exposidnc{symbol-text}@ Symbol, @\exposconceptnc{QuantityKindSpec}@ auto QS, @\libconcept{PointOrigin}@ auto PO>
   requires(!Symbol.empty()) && @\exposconceptnc{BaseDimension}@<std::remove_const_t<decltype(QS.dimension)>>
 struct named_unit<Symbol, QS, PO> : @\exposidnc{unit-interface}@ {
   using @\exposidnc{base-type}@ = named_unit;              // \expos
@@ -2427,21 +2564,21 @@
   static constexpr auto @\exposidnc{point-origin}@ = PO;   // \expos
 };
 
-template<symbol_text Symbol>
+template<@\exposidnc{symbol-text}@ Symbol>
   requires(!Symbol.empty())
 struct named_unit<Symbol> : @\exposidnc{unit-interface}@ {
   using @\exposidnc{base-type}@ = named_unit;           // \expos
   static constexpr auto @\exposidnc{symbol}@ = Symbol;  // \expos
 };
 
-template<symbol_text Symbol, @\libconcept{Unit}@ auto U>
+template<@\exposidnc{symbol-text}@ Symbol, @\libconcept{Unit}@ auto U>
   requires(!Symbol.empty())
 struct named_unit<Symbol, U> : decltype(U)::@\exposidnc{base-type}@ {
   using @\exposidnc{base-type}@ = named_unit;           // \expos
   static constexpr auto @\exposidnc{symbol}@ = Symbol;  // \expos
 };
 
-template<symbol_text Symbol, @\libconcept{Unit}@ auto U, @\libconcept{PointOrigin}@ auto PO>
+template<@\exposidnc{symbol-text}@ Symbol, @\libconcept{Unit}@ auto U, @\libconcept{PointOrigin}@ auto PO>
   requires(!Symbol.empty())
 struct named_unit<Symbol, U, PO> : decltype(U)::@\exposidnc{base-type}@ {
   using @\exposidnc{base-type}@ = named_unit;             // \expos
@@ -2449,7 +2586,7 @@
   static constexpr auto @\exposidnc{point-origin}@ = PO;  // \expos
 };
 
-template<symbol_text Symbol, @\libconcept{AssociatedUnit}@ auto U, @\exposconceptnc{QuantityKindSpec}@ auto QS>
+template<@\exposidnc{symbol-text}@ Symbol, @\libconcept{AssociatedUnit}@ auto U, @\exposconceptnc{QuantityKindSpec}@ auto QS>
   requires(!Symbol.empty()) && (QS.dimension == @\exposidnc{get-associated-quantity}@(U).dimension)
 struct named_unit<Symbol, U, QS> : decltype(U)::@\exposidnc{base-type}@ {
   using @\exposidnc{base-type}@ = named_unit;              // \expos
@@ -2457,7 +2594,7 @@
   static constexpr auto @\exposidnc{quantity-spec}@ = QS;  // \expos
 };
 
-template<symbol_text Symbol, @\libconcept{AssociatedUnit}@ auto U, @\exposconceptnc{QuantityKindSpec}@ auto QS,
+template<@\exposidnc{symbol-text}@ Symbol, @\libconcept{AssociatedUnit}@ auto U, @\exposconceptnc{QuantityKindSpec}@ auto QS,
          @\libconcept{PointOrigin}@ auto PO>
   requires(!Symbol.empty()) && (QS.dimension == @\exposidnc{get-associated-quantity}@(U).dimension)
 struct named_unit<Symbol, U, QS, PO> : decltype(U)::@\exposidnc{base-type}@ {
@@ -2536,7 +2673,7 @@
 \begin{codeblock}
 namespace mp_units {
 
-template<symbol_text Symbol, @\libconcept{Magnitude}@ auto M, @\libconcept{PrefixableUnit}@ auto U>
+template<@\exposidnc{symbol-text}@ Symbol, @\libconcept{Magnitude}@ auto M, @\libconcept{PrefixableUnit}@ auto U>
   requires(!Symbol.empty())
 struct prefixed_unit : decltype(M * U)::@\exposidnc{base-type}@ {
   using @\exposidnc{base-type}@ = prefixed_unit;                   // \expos