Glossary - E

4 A B C D F G H I K L M N O P R S T U V W X 

Echo:  See Command Echoing. 

Environment:  An area of memory which contains multiple entries in the 
form "NAME=value".  See also Master Environment and Passed Environment. 

Environment Variable:  The name of a single entry in the environment. 

Error Level:  A numeric value between 0 and 255 returned from an external 
command to indicate its result (e.g., success, failure, response to a 
question).  See also Exit Code. 

Escape Character:  In some contexts, the CMD.EXE escape character, which 
is used to suppress the normal meaning of or give special meaning to the 
following character.  In other cases, the specific ASCII character ESC. 
 The meaning must be determined from the context. 

Escape Sequence:  A sequence of text characters which has a special 
meaning and is not treated as normal text.  For example, the character 
sequence <ESC>]K (where <ESC> is the ASCII "escape" character, decimal 
value 27) will cause an ANSI driver to clear the screen from the cursor to 
the end of the current line, rather than simply displaying the string 
"ESC]K" on the screen.  Similarly, in CMD.EXE, the escape sequence ^f on 
the command line is translated to a form feed, and is not treated as the 
literal characters "^f". 

Executable Extensions:  A CMD.EXE feature which allows you to specify the 
application to be executed when a file with a particular extension is 
named at the command prompt. 

Executable File:  A file, usually with the extension .COM or .EXE, which 
can be loaded into memory and run as a program. 

Exit Code:  The result code returned by an external command or an internal 
command.  CMD.EXE internal commands return an exit code of 0 if 
successful, or non-zero if unsuccessful.  See also Errorlevel. 

Expansion:  The process CMD.EXE goes through when it scans a command line 
and substitutes the appropriate actual values for aliases, alias 
parameters, batch file parameters, and environment variables.  See also 
Parsing. 

Extended ASCII Character:  A character which is not part of the standard 
set of 128 ASCII characters, but is used on the PC as part of an extended 
set of 256 characters.  These characters include international language 
symbols, and box and line drawing characters. 

Extended Attributes:  An OS/2 High Performance File System (HPFS) feature 
which allows storage of additional information about a file, separate from 
the file itself.  Extended attributes are typically used to store icons 
for executable files, property or settings information, and other 
information added by the user. 

Extended Directory Search:  A CMD.EXE feature which maintains a directory search 
"database" or list, typically including all directories in your system, 
and allows you to change quickly to any directory in the list. 

Extended Key Code:  The code for a key on the PC keyboard which has no 
representation in the standard ASCII character set, such as a function 
key, cursor key, or Alt plus another key.  The extended key code for a key 
is often the same as the scan code for that key. 

Extended Memory:  Any memory on a computer system with a 286, 386, 486, or 
Pentium processor which is above the first 1 MB (one megabyte, or 
1024*1024 bytes) of memory.  See also XMS. 

Extended Parent Directory Names:  A CMD.EXE feature which allows you to 
use additional periods in a directory name to represent directories which 
are successively higher in the directory tree. 

Extended Wildcard:  A CMD.EXE feature which extends the traditional 
wildcard syntax and allows you to use multiple wildcard characters, and 
character ranges (e.g. [a-f] for the letters A through F).  See also 
Wildcard. 

Extension:  The final portion of a file name, preceded by a period.  For 
example, in the file name C:\DIR1\LETTER.DAT the extension is .DAT.  In a 
long filename which contains multiple periods, the extension is usually 
considered to be the portion of the name after the final period. 

External Command:  A program which resides in an executable file, as 
opposed to an internal command which is part of the command processor. 

EXTPROC:  A command processor feature which allows you to designate a 
specific external program to run a particular batch file.