In plain English
A recorded starting point used to compare later measurements after enough time has passed.
Why it matters
This instrument can help answer a focused measurement question when it is connected to a real objective and read alongside relevant context.
Example
A small organisation records this signal for a defined page and period, then compares it with related instruments before deciding whether to investigate a change.
Common misunderstanding
A fair baseline notes dates, conditions and measurement definitions; it is not a guarantee of what happens next.