Meaning of a sentence

[Honore]

Dear teacher,

Would you please explain what the following sentence tells and I'd really appreciate if you could please also point out the particular structure behind, if any?

Thanks and best regards

"The inner depth to exceed by 20 mm to 50 mm the overall depth of the refrigerating appliance, and shall not be more than 550 mm."

Source:
"Methods of measuring the energy consumption of electric mains
operated household refrigerators, frozen food storage cabinets,
food freezers and their combinations, together with associated
characteristics" - European Standard, February 2006

[MrPedantic]

Hello Honore

The to-infinitive here stands for "is to", which means "must", in this context.

As for the meaning...Let X = the appliance:

"The inside of X should be between 20 and 50mm deeper than X itself, and should not be more than 550mm in total."

(I don't entirely understand it; it seems to suggest that the inside of the freezer should be 20-50mm deeper than the freezer as a whole, which is clearly impossible. But perhaps there's a technical aspect which I've missed. If so, another member will put me right.)

All the best,

MrP

[curmudgeon]

Unless it is referring to a housing or cabinet that the appliance is situated in.

[Honore]

Dear teachers,

Thanks a lot for the explanations. I have re-checked the standard and seen those two previous sentences I overlooked. They say:

"Refrigerating appliances shall be built-in or placed in a test enclosure."

"The inner dimensions of the test enclosure are as follows:"

Now, it seems logical.

Please excuse me, and kindest regards.

[MrPedantic]

MrP