Packet Size - Variable (one packet per atom type)
| IDN | Description |
| 1 | number of atoms of this type per unit cell |
| 2 | atomic weight |
| 3 | atomic number |
| 4 | number of electrons in neutral atoms or ions |
| 5 | atomic bond radius in Angstroms |
| 6 | atomic contact radius in Angstroms |
| 7 | flag if interpolated scat. factors are stored in refl 0/1 = no/yes |
| 9 | effective spin quantum number |
| 10 | neutron scattering length in cm*10-12 |
| 11 | atom type symbol1 (8 characters) |
| 12-20 | Cromer-Mann coefficients a1, b1, a2, b2, a3, b3, a4, b4, c |
| 21-45 | real part of dispersion scattering factor for data sets 1 to 25 |
| 61-85 | imaginary part of dispersion scattering factor for data sets 1 to 25 |
| 95 | source of scattering data1 (40 characters) |
| 98 | mass percentage of element from chemical analysis |
| 99 | e.s.d. of mass percentage in IDN 98 |
| 100 | atomic scattering factor2 at s = 0.00 |
| 101 | atomic scattering factor at s = 0.01 |
| 102 | atomic scattering factor at s = 0.02 |
| . . . | . . . . . . . . . . . . |
| 299 | atomic scattering factor3 at s= 1.99 |
| 1 This ID number will be repeated for each word required tocontain the character string. | |
| 2 Scattering factors at s-intervals of 0.01 need NOT bepresent. The fineness of the table is optional. | |
| 3 Additional scattering factors for a given atom type arestored in 300-499, 500-699, 700-899, ... | |