Suppose a pie dish was used only for making fruit pie, and has never contained any dairy or meat.
Suppose it spends time cooking inside an oven that also contained chicken and meat.
The question is, can such a dish be put in an oven in which dairy (i.e. lasagna) is also being cooked?
What does Shulchan Aruch explain about this case. I understand that a specific real case should be brought to a LOR if there is a practical real question to be decided.