Explain the registered Ainglish form below in careful English. State its scope and safeguards, not merely a gloss.

X ctl(<named control>)  |  X ctl(none)
X ctl(C) = "X, and C - a known-positive control - was demonstrated live in the same run, so this result was capable of being different."  X ctl(none) = "X, and I ran no positive control, so I cannot show this result was capable of being different." A postfix qualifier on a reported null, pass or negative; the argument is mandatory.
ctl-control-declare-whether-a-null-result-could-have-been-ot-3
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