[Grammar] Relevant protocols and band design of this device are tested

[kadioguy]

(On a cellphone case)

Relevant protocols and band design of this device are tested and set according to the requirements of the Internet Service Provider (ISP) in Taiwan.

The compatibility in other areas is subject to the band and communication services provided by the Internet Service Provider (ISP) in Taiwan.
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1. Why isn't there a the before the red part, while there is one before the green part? How can I tell whether a "the" is necessary?

2. Why is the "are" used, rather than "were"? Didn't this test happen in the past? Or maybe the "tested (and set)" is here more like an adjective?

What do you think?
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(Source)

 

[Charlie Bernstein]

(On a cellphone case)

Relevant protocols and band design of this device are tested and set according to the requirements of the Internet Service Provider (ISP) in Taiwan.

The compatibility in other areas is subject to the band and communication services provided by the Internet Service Provider (ISP) in Taiwan.
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1. Why isn't there a the before the red part,

It's not needed. You don't always need articles.

while there is one before the green part?

It's optional there, too.

How can I tell whether a "the" is necessary?

Why do we say "a cold" but "the flu" but "pneumonia"? I don't know. There might be guidelines, but if there are, I don't know them.

2. Why is the "are" used, rather than "were"?

Either way is fine. Using "are" means they're explaining how they're done: in accordance with the ISP.

Didn't this test happen in the past? Or maybe the "tested (and set)" is here more like an adjective.

They're both verbs there.

What do you think?

That's the best I can do. Let's see what others can add.

 

[kadioguy]

(On a cellphone case)

Relevant protocols and band design of this device are tested and set according to the requirements of the Internet Service Provider (ISP) in Taiwan.

[...]

I assume that "this device" means all phones of this model, so the "are" means that phones of this model are still produced; they are tested and set according to the requirements of the Internet Service Provider (ISP) in Taiwan.

Is this reasonable?

 

[Charlie Bernstein]

Yes, very reasonable. You are exactly right.