SKILL.md

ebcdic-overpunch-decoding

Agent skill frombenchflow-ai/skillsbench

Reference for the EBCDIC "overpunch" / zoned-decimal sign convention where the units position of a numeric field is replaced with a letter that encodes both a digit and a sign. Useful when reading mainframe-style fixed-length tapes whose amount fields appear as digits followed by a letter (e.g. "0000000000123D" or "0000000000045M").

install ebcdic-overpunch-decoding

# install the skillsbench pack with the skills CLI

npx skills add benchflow-ai/skillsbench

# or add only this skill to Claude Code: copy the folder

tasks-extra/cobol-gl-batch-reconcile/environment/skills/ebcdic-overpunch-decoding/

# into

~/.claude/skills/ebcdic-overpunch-decoding/ (all projects)

.claude/skills/ebcdic-overpunch-decoding/ (one project)

tasks-extra/cobol-gl-batch-reconcile/environment/skills/ebcdic-overpunch-decoding/SKILL.md

Apache-2.0Full file

1# EBCDIC overpunch (zoned decimal sign)
2 
3On classic mainframe tapes, signed numeric amounts are stored as N-1 digits
4followed by a single byte where the high-order bits carry the sign and the
5low-order bits carry the final decimal digit. When the file is converted to
6ASCII / printable form, the last byte is rendered as a letter (or a brace).
7 
8## Sign and digit table
9 
10| Char | Sign | Last digit |       | Char | Sign | Last digit |
11|------|------|------------|-------|------|------|------------|
12| `{`  |  +   | 0          |       | `}`  |  −   | 0          |
13| `A`  |  +   | 1          |       | `J`  |  −   | 1          |
14| `B`  |  +   | 2          |       | `K`  |  −   | 2          |
15| `C`  |  +   | 3          |       | `L`  |  −   | 3          |
16| `D`  |  +   | 4          |       | `M`  |  −   | 4          |
17| `E`  |  +   | 5          |       | `N`  |  −   | 5          |
18| `F`  |  +   | 6          |       | `O`  |  −   | 6          |
19| `G`  |  +   | 7          |       | `P`  |  −   | 7          |
20| `H`  |  +   | 8          |       | `Q`  |  −   | 8          |
21| `I`  |  +   | 9          |       | `R`  |  −   | 9          |
22 
23Positive zero is `{`; negative zero is `}`. Both decode to magnitude 0 — keep
24the sign attached so downstream arithmetic doesn't drop a debit's polarity.
25 
26## A common defect
27 
28The positive half of the table (`{`, `A`–`I`) is the visible-looking case and
29is often handled first. The negative half (`}`, `J`–`R`) looks like ordinary
30…

Excerpt shown under the repository's Apache-2.0 license.

How to install ebcdic-overpunch-decoding

tasks-extra/cobol-gl-batch-reconcile/environment/skills/ebcdic-overpunch-decoding/SKILL.md

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