Hulle verkoop kos, met dien verstande dat die datummerk duidelik is.

It is a fixed, formal expression meaning provided that, on condition that, or with the understanding that.

In other words, it introduces a condition. In this sentence, the selling happens only under that condition.

This phrase is especially common in formal, official, legal, or administrative language.

Dien is part of this fixed expression. It is an older, formal form that survives in set phrases like met dien verstande dat.

So for a learner, the best approach is:

• learn met dien verstande dat as one chunk
• do not try to build it freely with normal modern article rules

In everyday Afrikaans, you would not normally use dien like this outside such fixed expressions.

Yes. It is related to verstand, which normally means understanding, sense, or mind.

In met dien verstande dat, the form verstande is part of the frozen idiom. It is not something learners usually need to produce separately in ordinary speech.

So again, it is best to treat met dien verstande dat as a set phrase rather than trying to analyze each word too literally.

No, it is completely correct.

They are two different words with two different jobs:

• dat = the conjunction that, introducing a subordinate clause
• die = the definite article the

So:

• dat die datummerk duidelik is
• that the date marking is clear

This sequence is very common in Afrikaans.

Because dat introduces a subordinate clause, and in Afrikaans subordinate clauses the finite verb usually goes to the end.

So the pattern is:

• main clause: Hulle verkoop kos
• subordinate clause after dat: die datummerk duidelik is

Compare:

• main clause: Die datummerk is duidelik
• subordinate clause: ... dat die datummerk duidelik is

This is one of the most important word-order patterns in Afrikaans.

Datummerk is a compound noun:

• datum = date
• merk = mark / marking / label

Afrikaans very often forms compound nouns by writing them as one word.

So datummerk is literally a kind of merk. Depending on context, it could mean something like:

• date mark
• date label
• date stamp
• expiry-date marking

The exact English translation can vary a bit depending on the situation.

In Afrikaans, verbs usually do not change form for person or number in the present tense.

So you get:

• Ek verkoop
• Jy verkoop
• Hy verkoop
• Ons verkoop
• Hulle verkoop

This is much simpler than English, where you have forms like I sell but he sells.

Here kos means food in a general sense, so it is being used as an uncountable noun.

That is very normal in Afrikaans.

So:

• kos = food in general

There is also kosse, but that is more like foods or dishes in specific contexts, not the usual choice for general food.

Because duidelik is being used predicatively, after the linking verb is.

In Afrikaans, adjectives used after is, bly, lyk, and similar verbs usually stay in the basic form:

• Die datummerk is duidelik

But before a noun, you often get the -e form:

• 'n duidelike datummerk

So:

• after the verb: duidelik
• before the noun: duidelike

It sounds fairly formal, especially because of met dien verstande dat.

In everyday speech, many speakers would choose something simpler, such as:

• Hulle verkoop kos, solank die datummerk duidelik is.
• Hulle verkoop kos op voorwaarde dat die datummerk duidelik is.
• Hulle verkoop kos mits die datummerk duidelik is.

So the original sentence is correct, but it has an official or written tone.

The comma helps separate the main statement from the added condition.

Structure:

• main clause: Hulle verkoop kos
• added conditional phrase: met dien verstande dat die datummerk duidelik is

This punctuation is natural and helpful, especially in formal writing and with longer inserted phrases like this one.

Not directly, if you want the same formal conditional meaning.

As usually means if or when, and it does not have the same formal provided that / on condition that force.

For example:

• as = if
• met dien verstande dat = provided that / on condition that

So they are related in meaning, but not really interchangeable in tone or exact use.