Symbols

    A symbol represents a value, which can be a variable, address label,
    or an operand to an assembly instruction or directive.


    Symbol names

    Symbol names are combinations of letters (both uppercase and
    lowercase), digits, and special characters. Symbol names can't start
    with a digit. TASM treats symbols as either case sensitive or case
    insensitive. The command line switches /ml, /mu, and /mx control the
    case sensitivity of symbols.

    Symbol names can be up to 255 characters in length. By default,
    symbol names are significant up to 32 characters. You can use the /mv
    command line switch to change the number of characters of
    significance in symbols.

    The underscore (_), question mark (?), dollar sign ($), and at-sign
    (@) can all be used as part of a symbol name. In MASM mode only, you
    can use a dot (.) as the first character of a symbol name. However,
    since it's easy to confuse a dot at the start of a symbol with the
    dot operator (which performs a structure member operation), it's
    better not to use it in symbol names.


    Symbol types

    Each symbol has a type that describes the characteristics and
    information associated with it. The way you define a symbol determines
    its type. For example, you can declare a symbol to represent a numeric
    expression, a text string, a procedure name, or a data variable. The
    following table lists the types of symbols that Turbo Assembler v4.0
    supports.


    Symbol type         Description
    ───────────────────────────────────────────────────────────────────
    address             An address
                        Data subtypes are:
                          UNKNOWN,BYTE,WORD,DWORD,PWORD or FWORD,QWORD,
                          TBYTE, and an address of a named structure
                          or table
                        Code subtypes are:
                           SHORT, NEAR, and FAR
    text_macro          A text string
    alias               An equivalent symbol
    numerical_expr      The value of a numerical expression
    multiline_macro     Multiple text lines with dummy arguments
    struc/union         A structure or union data type
    table               A data table type
    struc_member/
      table_member      A structure or table member
    record              A record data type
    record_field        A record field
    enum                An enumerated data type
    segment             A segment
    group               A group
    type                A named type                 (cf. TYPEDEF directive)
    proceduretype       A procedure description type (cf. PROCTYPE directive)