Payee
What it is
Identifies the payee in payment/transfer transactions.
DE 98 on the wire
Bitmap position
DE 98 is bit 34 of the secondary bitmap: byte 5, mask 0x40. A secondary bitmap with only DE 98 present reads 0000000040000000 in hex. The secondary bitmap is only sent when bit 1 of the primary bitmap is set, so any message carrying DE 98 has a primary bitmap whose first hex digit is 8 or higher.
Length
DE 98 is fixed length: always 25 characters, with no length prefix. A parser reads exactly that many and moves on, so shorter values are left-aligned and padded with trailing spaces.
Size in the message
At most 25 bytes when the message travels as text (ASCII or EBCDIC).
Format ans
Format ans means alphanumeric and special: letters, digits, space and punctuation.
Specification reference
Defined in ISO 8583:1987 (base). Card networks publish their own dialect tables (Visa BASE I / V.I.P., Mastercard CIS) that refine formats, lengths, and — for private-use elements — the entire layout. Always confirm against the interface specification you implement.