As stated already this is the ECSC not the ECC.
If the 3rd bullet point under 92.1 is stated as 'not used' then any amounts retained at the time of termination would not be included in an assessment of the amount due. This 'retained' amount could include 'retention', as stated in Contract Data, or an amount for not submitting a programme, as stated at clause 50.7.
Although the retained amount should be comparatively small in your case, as only preliminary works have taken place, also assuming there is no 'programme retention', this still highlights the importance of a thorough review of the contract terms and conditions to assess the commercial risk, prior to signing.
In your case, upon termination you would be paid;
A. - a 'normal payment' amount,
B. - cost of Plant and Materials,
C. - ((forecast of the amount that would have been due at Completion) less A.) x 5%.