Input Message File Format

The input message file is a standard ASCII file containing three types of lines:

Comment lines
Component identifier line
Component message lines

Comment Lines

Comments may appear anywhere in the file except between the component identifier line and the first message line. A comment line must begin with a semicolon (;) in the first column.

Example:

; This is a sample of an input
; message file for component DOS
; starting with three comment lines.

Component Identifier Line

A single line holding the three‑character component identifier. This identifier is prefixed to all message numbers generated by MKMSGF.

In the example, the identifier is DOS.

Component Message Lines

Each message line consists of a message header followed by the ASCII text of the message.

Message Header

The header is composed of the following fields, written contiguously:

Three‑character component identifier (e.g., DOS).
Four‑digit message number (e.g., 0100).
A single character indicating the message type (see table below).
A colon (':').
A single blank space separating the header from the message text.

Format: COMPNNNNT: message text

Message Types

Code	Type	Meaning
E	Error	Error message
H	Help	Help text
I	Information	Informational message
P	Prompt	Prompt (user input expected)
W	Warning	Warning message
?	(unused)	Placeholder for a number with no message text

Numbering and Placeholder Entries

Message numbers may start at any value, but must appear in strictly ascending sequential order in the file.
When a particular number is not used, a placeholder entry is required. A placeholder consists of the full header with the type ? and no message text after the colon and blank.

Example: MAB0101?:

Special Characters in the Message Text

The percent sign (%) has special meaning when used inside message text.

Suppressing the Trailing Newline (''%0'')

If the sequence %0 appears as the very last characters of a message text, the DosGetMessage API will not append a carriage return and line feed (CR+LF). This is typically used for prompts so that user input can follow on the same line.

Inserting Variable Strings (''%1'' – ''%9'')

Sequences %1 through %9 mark positions where variable strings are inserted at runtime. The actual values are provided via the Itable and IvCount parameters of the DosGetMessage call.

Example: the message %1 files copied will have %1 replaced by an appropriate string (e.g., a number of files).

Complete Input File Example

; This is a sample of an input
; message file for component MAB
; starting with three comment lines.
MAB
MAB0100E: File not found
MAB0101?:
MAB0102H: Usage: del [drive:][path] filename
MAB0103?:
MAB0104I: %1 files copied
MAB0105W: Warning! All data will be destroyed!
MAB0106?:
MAB0107?:
MAB0108P: Do you wish to apply these patches (Y or N)? %0
MAB0109E: Divide overflow

MAB – component identifier.
MAB0100E – error message.
MAB0101? – placeholder for an unused number.
MAB0104I – informational message with variable insertion (%1).
MAB0108P – prompt with %0 to suppress the trailing newline.

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