A-LevelComputer ScienceSystem software9618/31 · May/June 2025 · Q76 Marks

Several syntax diagrams are shown. [Figure showing syntax diagrams for uppercase, lowercase, symbol, digit, passcode]

(a)State why each passcode is invalid for the given syntax diagrams. #Jd7 Reason C%6A Reason[2]
(b)Complete the Backus-Naur Form (BNF) for <uppercase> and <passcode>. <uppercase> ::= <passcode> ::=[4]

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Mark scheme

Marking points from the official mark scheme (May/June 2025). The mark or mark type is shown in brackets.

[1] For #Jd7: must begin with a member of the group uppercase // cannot begin with a symbol
[1] For C%6A: the fourth character cannot be a member of the group uppercase // the fourth character must be either a symbol, digit or lowercase
[1] <uppercase> ::= A | C | E | G | J
[1] <passcode> ::= <uppercase><code>
[1] <code> ::= <lowercase>|<symbol>|<digit>
[1] <code> ::= <lowercase><code>|<symbol><code>|<digit><code>

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About this question

Topic

System software, A-Level Computer Science (syllabus 9618). Structured question, 6 marks.

Source

A-Level Computer Science, May/June 2025 Paper 3 Variant 1, question 7.

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