Are candidates expected to able to write code for and use random files on Paper 4 (programming practical)?

In respect to writing code for operations on random files for Paper 4, on page 40 of the Computer Science syllabus (9618) it states, the source files given will not contain binary files. Candidates will be given .txt source file(s) and this is separate from the evidence.doc where candidates' document their answers.  They will be expected to produce a hashing algorithm and access data from another data structure to simulate random files.