In COBOL using a COMP (computational) field, how is the sign of a numeric value typically stored?

Introduction / Context:
In COBOL, numeric data can be stored in various formats, including DISPLAY, COMP, and COMP-3. COMP fields are computational binary fields optimized for arithmetic operations. Understanding how the sign is stored in these fields is important for low level data interpretation, debugging, and interoperability with other systems. This question focuses on how the sign is represented in a COMP field.

Given Data / Assumptions:

• The language is COBOL and the data type is COMP, also called computational binary.
• We are interested in the representation of the sign (positive or negative).
• The value is stored in binary rather than decimal text.
• We assume typical mainframe COBOL implementation details.

Concept / Approach:
COMP fields store numeric values in pure binary form. For signed binary integers, the sign is included in the bit pattern itself. Many implementations use two's complement representation, where the high order bit indicates the sign. A high order bit of 0 typically means positive, and 1 means negative. There is no separate character position for the sign when using COMP. Therefore, the correct answer must describe the sign encoded in the high order bit of the binary value, not in a separate column or as text symbols.

Step-by-Step Solution:
1. Recall that COMP fields are binary, which means values are stored as bits rather than as packed or display digits. 2. Understand that signed binary integers usually use two's complement, embedding the sign into the bit pattern. 3. Recognize that the most significant bit (high order bit) often indicates whether the value is positive or negative. 4. Review the options and look for the one that describes the sign being stored in the high order bit of the binary representation. 5. Reject options that talk about separate character fields or about COMP not supporting negative numbers.

Verification / Alternative check:
As a verification, consider how arithmetic is performed on COMP fields. Because they are binary, operations like addition and subtraction rely on the two's complement representation, which naturally includes the sign. No extra parsing of a sign character is needed. This is quite different from DISPLAY numeric fields, where signs may be stored as characters. This contrast confirms that the sign is embedded in the binary value for COMP fields, matching the high order bit description.

Why Other Options Are Wrong:

• Option B is wrong because having a separate character field for the sign would be more typical of some custom formats, not standard COMP representation.
• Option C is wrong because plus and minus text symbols are associated with DISPLAY formats, not with binary COMP fields.
• Option D is wrong because COMP fields can indeed represent negative numbers; they are not limited to positive values.

Common Pitfalls:
A common misunderstanding is to assume that all COBOL numeric types use the same storage structure. In reality, DISPLAY, COMP, and COMP-3 each have different layouts. Another pitfall is assuming that the sign is always visible as a character when examining raw data, which is not true for binary formats. Knowing how COMP fields are stored helps when using tools like dump analyzers or when interfacing COBOL programs with non COBOL systems that must interpret the binary fields correctly.

Final Answer:
The correct answer is The sign is stored in the high order bit of the binary representation of the COMP field, because this reflects how signed binary values, including COBOL COMP integers, typically encode positive and negative signs within the bit pattern.