A digital link is any transfer of data between systems that happens without a human retyping or copy-pasting it. Formulas between spreadsheet cells, linked workbooks, CSV imports, API connections and bank feeds all count. Typing, copying and pasting do not. It matters at setup because digital links are where most compliance problems are designed in: if your till exports a sales total that someone keys into a bookkeeping package every Monday, you have built a break in the chain that will still be there at your first inspection. So a proper setup traces the whole path from where a transaction is first recorded to where it reaches HMRC and makes sure every hop is automated. The soft-landing period that once allowed copy-paste has long since ended.