phrase - Nächster planmäßiger Halt ist ...
December 5, 2019
December 6, 2019
Weak: following der, die or das
Mixed: following ein, kein
Strong: neither der,die das, or ein, kein are present
There is a lesson on this in 10.8
In your phrase:
There is no der die das so you need the strong set of endings.
The first adjective does not "become" dieser, you need the strong endings on all the adjectives.
December 9, 2019
sfpugh is right, there are three different categories which determine adjective endings:
1. Adjectives preceded by an definite article (der, die, das) or demonstrative pronoun (dieser, jener, solcher, etc.), for example:
"Der nächste fahrplanmäßige Halt ist Frankfurt." - "The next scheduled stop is Frankfurt."
2. Adjectives preceded by an indefinite article (ein, eine), kein, or possessive determiner (mein, dein, sein, etc.), for example:
"Ein großer Zug fährt nach Frankfurt." - "A big train is travelling to Frankfurt."
3. Adjectives not preceded by an article or other modifiers
In your phrase above
"Nächster fahrplanmäßiger Halt ist Frankfurt." - "Next scheduled stop is Frankfurt."
the two adjectives nächster and fahrplanmäßiger stand alone in front of the noun Halt, so their endings have to agree with the gender, number and case of the noun. You could say they have to act as both, the adjective and article.
Also, please note fahrplanmäßiger shouldn't be capitalised as it's an adjective. I have passed this on to get corrected in the lesson.
Hope this clears things up!