MODS definitions, based vs. non-based, V4R5

Anybody know why this occurs?  Situation:

File with record length of 47.  In one module, used as an externally
described MODS, but not based.  In called module, used as MODS, but based.
The file for the EDS is defined in called module.  The data structures get
different lengths.  Compile listing of calling module:


Dsccc5dds       e ds                  extname(SCCC5D) occurs(50)

SCCC5DDS(50)      DS(64)                 37D


But in the called module:


DxdSCCC5D       E DS                  EXTNAME(SCCC5D) OCCURS(500)
D                                     based(pC5D)

XDSCCC5D(500)     DS(47)                 19D
                  BASED(PC5D)


As I said, SCCC5D is also defined in a file specification in the called
module.  Why did the DS get a length of 64 in the calling module but yet got
the correct length of 47 in the called module?  As you might guess, this
causes some serious communication problems between the two.

Joe