Proposed resolution:

Change "3.2.2 Class decimal32" as follows:

      namespace std {
      namespace decimal {
        class decimal32 {
          public:
            // 3.2.2.1 construct/copy/destroy:
            decimal32();
            decimal32(const decimal32 & d32);
            decimal32 & operator=(const decimal32 & d32);
            ~decimal32();
            /* ... */

Change "3.2.2.1 construct/copy/destroy" as follows:

        decimal32();

    Effects: Constructs an object of type decimal32 with the value 0;

        decimal32(const decimal32 & d32);
        decimal32 & operator=(const decimal32 & d32);

    Effects: Copies an object of type decimal32.

        ~decimal32();

    Effects: Destroys an object of type decimal32.

Change "3.2.3 Class decimal64" as follows:

      namespace std {
      namespace decimal {
        class decimal64 {
          public:
            // 3.2.3.1 construct/copy/destroy:
            decimal64();
            decimal64(const decimal64 & d64);
            decimal64 & operator=(const decimal64 & d64);
            ~decimal64();
            /* ... */

Change "3.2.3.1 construct/copy/destroy" as follows:

        decimal64();

    Effects: Constructs an object of type decimal64 with the value 0;

        decimal64(const decimal64 & d64);
        decimal64 & operator=(const decimal64 & d64);

    Effects: Copies an object of type decimal64.

        ~decimal64();

    Effects: Destroys an object of type decimal64.

Change "3.2.4 Class decimal128" as follows:

      namespace std {
      namespace decimal {
        class decimal128 {
          public:
            // 3.2.4.1 construct/copy/destroy:
            decimal128();
            decimal128(const decimal128 & d128);
            decimal128 & operator=(const decimal128 & d128);
            ~decimal128();
            /* ... */

Change "3.2.4.1 construct/copy/destroy" as follows:

        decimal128();

    Effects: Constructs an object of type decimal128 with the value 0;

        decimal128(const decimal128 & d128);
        decimal128 & operator=(const decimal128 & d128);

    Effects: Copies an object of type decimal128.

        ~decimal128();

    Effects: Destroys an object of type decimal128.