WWIV BBS historically supports type-1 and type-2 message areas. The type-1 message area was the original type implemented in WWIV 3.21 and consists of 1 file for the header of all messages in an area, and 1 file per message containing the text of the message.

Type2 messages share the same 100 byte postrec for the headers in a SUBNAME.SUB file as type-1 message areas. The Text are contained in a single file named SUBNAME.DAT that lives in the MSGS directory.

On disk, the format is:

GAT | 2048 512-byte message blocks | [ GAT | 2048 512-byte message blocks ]*

The GAT is similar to the FAT table of a MS-DOS disk.

GAT: 2048 2-byte integers for the index of the message blocks. Let's say the message was stored in in gat #0 in blocks 1, 3, and 5, then the gat would contain:

block:  0   1   2   3   4   5
value: -1   3  -1   5  -1  -1