Dated from September 1999
| Files | Description | Approx. object file size (KB) * | Mode | Platforms | Include | Comments |
| argv.c | Externals for class ARGUMENTS | 0.9 | WK/F | any | Optional | Executable with arguments |
| bits.c | Eiffel bits management routines | 4.9 | WK/F | any | Optional | |
| boolstr.c | Externals for class BOOL_STRING | 0.9 | WK/F | any | Optional | |
| cecil.c | C-Eiffel Call-In library | 2.5 | WK/F | any | Required | Require hector.c |
| compress.c | Compression/Decompression algorithms | 1.1 | WK/F | any | Optional | Mostly internal use |
| console.c | Externals for class CONSOLE | 0.9 | WK/F | any | Recommended | Standard I/O |
| copy.c | Multiple copy routines | 3 | WK/F | any | Necessary | |
| debug.c | Debugging control | 4.1 | WK/F | any | Optional | Not available in Finalized mode |
| dir.c | Externals for directory handlings | 1.2 | WK/F | any | Optional | |
| dle.c | Dynamic Linking in Eiffel | 0.7 | WK/F | any | Optional | Obsolete |
| eif_cond_var.c | Condition variables for Windows | WK/F | Windows | Optional | Only in Multi-threaded mode | |
| eif_once.c | Once per process management routines | 2.8 | WK/F | any | Optional | Only in Multi-threaded mode |
| eif_project.c | Interface for generating DLL. | 0.4 | WK/F | any | Necessary | |
| eif_threads.c | Threads management routines | 6.2 | WK/F | any | Optional | Only in Multi-threaded mode |
| eif_rw_lock.c | Read write locks management routines | 1.6 | WK/F | any | Optional | Only in Multi-threaded mode |
| equal.c | Equality C externals | 2.3 | WK/F | any | Necessary | |
| error.c | System error handling | 0.6 | WK/F | any | Necessary | |
| eif_special_table.c | Big array optimization routines | 2.1 | WK/F | any | Optional | Only with hybrid marking |
| except.c | Exception handlings | 11.8 | WK/F | any | Necessary | |
| file.c | External for class FILE | 7 | WK/F | any | Recommended | I/O operations |
| garcol.c | Garbage Collector core | 12.7 | WK/F | any | Necessary | |
| gen_conf.c | Generic conformance routines | 14.3 | WK/F | any | Necessary | Since version 4.3 |
| hash.c | Hash-table management routines | 0.8 | WK/F | any | Recommended | |
| hashin.c | Hash-table with integer keys routines | 1.6 | WK/F | any | Recommended | |
| hector.c | Eiffel-C transfer of objects to routines | 1.6 | WK/F | any | Necessary | require cecil.c |
| internal.c | Externals for class INTERNAL | 1.7 | WK/F | any | Optional | Internal structures of Eiffel objects |
| interp.c | Eiffel interpreter routines | 28.2 | WK | any | Necessary | |
| lmalloc.c | Internal Eiffel malloc library | 0.7 | WK/F | any | Necessary | |
| local.c | Local variables stack handling | 1.2 | WK/F | any | Necessary | |
| main.c | Eiffel run-time initialization routines | 6.5 | WK/F | any | Necessary | |
| malloc.c | Eiffel allocation management routines | 9.2 | WK/F | any | Necessary | |
| math.c | Externals for class SINGLE_MATH | 0.8 | WK/F | any | Optional | |
| memory.c | Externals for class MEMORY | 1.8 | WK/F | any | Optional | To customize the Garbage Collector |
| misc.c | Miscellaneous Eiffel externals | 1.1 | WK/F | any | Optional | |
| object_id.c | External for class OBJECT_ID | 1.5 | WK/F | any | Optional | Only on specific purpose |
| option.c | Option queries, profiler core, tracer core | 3.6 | WK/F | any | Optional | |
| out.c | Routines for printing Eiffel objects | 3.8 | WK/F | any | Recommended | |
| path_name.c | Pathname manipulation. | 1 | WK/F | any | Optional | |
| pattern.c | Pattern matching routines | 1.2 | WK/F | any | Optional | |
| retrieve.c | Retrieval of stored objects routines | 30.2 | WK/F | any | Optional | |
| rout_obj.c | Routine objects management routines | 0.9 | WK/F | any | Optional | Since version 4.3 |
| run_idr.c | Internal Data Representation routines | 4.5 | WK/F | any | Optional | Internal use |
| search.c | Search table management routines | 0.9 | WK/F | any | Necessary | |
| sig.c | Signals handling | 3.7 | WK/F | any | Necessary | |
| store.c | Storing mechanism | 10.3 | WK/F | any | Optional | |
| string.c | Externals for class STRING | 2.4 | WK/F | any | Recommended | String manipulation |
| tools.c | General purpose tools | 0.7 | WK/F | any | Optional | |
| timer.c | Time related routines | 0.8 | WK/F | any | Optional | |
| traverse.c | Traversal of objects | 1.4 | WK/F | any | Necessary | |
| umain.c | User customized main entry | 0.4 | WK/F | any | Optional | |
| update.c | Interpreted data update primitive | 5.4 | WK | any | Necessary | Internal use |
| urgent.c | Urgent memory handling | 0.7 | WK/F | any | Necessary | Internal use |
| wbench.c | Workbench primitive | 2.8 | WK | any | Necessary |