| BlockNo. | Block Name | Block Code | Notes |
| 17 | Name of Referring Physician or Other Source | M | Enter the name and the degree of the attending practitioner. |
| 17a | I.D. Number of Referring Physician | A | In the first portion of this block, enter a two-digit qualifier that indicates the type of ID: 0B = License Number 1D = 13-digit Provider ID number (Legacy Number) In the second portion, enter the license number of the referring or prescribing practitioner named in Block 17 (e.g., MD123456X). If the practitioner's license number was issued after June 29, 2001, enter the number in the new format (e.g., MD123456). If an out-of-state provider orders the service, enter the two-letter State abbreviation, followed by six 9’s, and an X. For example, a prescribing practitioner from New Jersey would be entered as NJ999999X. |
| 17b | NPI # | A | Enter the 10-digit National Provider Identifier number of the referring provider, ordering provider, or other source. |
| 18 | Hospitalization Dates Related to Current Services | LB | Do not complete this block. |
| 19 | Reserved For Local Use | A/A | This field must be completed with attachment type codes, when applicable. Attachment type codes begin with the letters “AT”, followed by a two- digit number (i.e., AT05). Enter up to four, 4-character alphanumeric attachment type codes. When entering more than one attachment type code, separate the codes with a comma (,). |
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