To provide the most compact file storage, bcp precedes each field, except those defined as char, with a string of one or more characters that indicate the length of the field. The default values in the prompts indicate the most efficient prefix lengths.
For fields of 255 characters or less, the default prefix length is 1. For text or image datatypes, the default prefix length is 4. When binary and varbinary datatypes are being converted to char storage types, the default prefix length is 2, since 2 bytes of storage are required for each byte of table data.
To store data with no prefix before the column, use a prefix length of 0. Each stored field is padded with spaces to the full length specified at the next prompt for length of field.