When the Eyecatcher is 'IRX8', the Level field specifies the format of the extension. If it is set to 0, elements defined for 64-bit implementation are used. If it is set to 1, elements defined for APH implementation are used.
| Extension Head | Eyecatcher | Level | Element Structures Used |
|---|---|---|---|
| D8CAIRX | IRX8 | 0 | D8XILMNT, D8XILPTR |
| D8CAIRX | IRX8 | 1 | D8XIELEM, D8XIEP |
Use of value 0 is deprecated. New implementations should use the elements defined for APH implementation.