The Data Collection Form (Case report Form, CRF) is the primary data collection instrument. Data management check will take place and missing data will be explained where possible. If the item is not applicable to the individual case, N/A will be written. All entries will be printed legibly in black ink. If any entry error has been made, to correct the error, a single line will be drawn through the incorrect entry and the correct data entered above it. All such changes will be initialled and dated. For clarification of illegible or uncertain entries, the clarification will be printed above the item and this will be initialled and dated.