EBCDIC stands for Extended Binary Coded Decimal Interchange Code, and is the character set used by most IBM mainframes to store documents (in preference to the more commonly used ASCII character set).
If you try to view an EBCDIC file with a standard ASCII file viewer/editor (eg, notepad), the text will appear as a stream of unprintable control characters. For example, the EBCDIC code for the number zero is hex F0, which is not a printable character in ASCII.
When V opens a file, it automatically tries to determine if it is ASCII or EBCDIC. If a file is EBCDIC, EBC will be displayed on the bottom status bar.
If an EBCDIC file is incorrectly displayed as ASCII, you can view it as EBCDIC by pressing Alt+B (or selecting EBCDIC from the View menu).
Once in EBCDIC mode, you may modify EBCDIC viewing options by selecting EBCDIC Options from the View menu, or by clicking on EBC in the status bar.
V views EBCDIC files by mapping each EBCDIC character to the ASCII equivalent before displaying. However, there are at least 6 incompatible versions of EBCDIC (all having non-contiguous letter sequences and missing punctuation characters). In order to support all of these mappings (and more), V defines a default mapping which can then be modified in the EBCDIC tab of the Preferences.
V supports files with variable length records (RECFM=V) and fixed length records (RECFM=F).