There are certain Dharmas which are constant, like Truth,Compassion.
The Dharma of a Brahmana is at variance with that of a Kshatriya;when insulted or provoked a Kshatriya must attack, a Brahmin must bear with them.
Keeping quiet when speaking the Truth is sometimes called Dharma.
Dharma varies according to the stages of Life,Brahmachari’s is different from Gruhasha and Gruhstha’s is different form Vanaprastha for identical situations.
So much so Lord Krishna says it vey difficult to say what Dharma is even for a very leaned man(Bhagavad Gita)
Yet there is a reasonably detailed description of what Dharma is in in Bruhat Purana.
‘ sathyam Dhaya thataha santhirahimsa cheti keerthitha,
Dharmasyaavayavaastha chatvaarah poornatham gatha.
Twelve different forms of Sathya (Truth).
‘Amityavachanam satyam Sweekaarapradhipaalanam,
Priyavaakyam kuroh Seva Dhrdam chaiva vrataham Kruham’
Aasthikyam Saadhusangasya Pitur maathu piyankarah
Suchithvam,dwividam chaiva hreerasanchaya eva Cha’
1.Amitavachanam-not speaking that which is not true.
2.Sathyam-Truth,Not speaking a fact is different from speaking the fact as it is.
3.Sweekaarapradhipaalanam-Completing what one has undertaken to do.
4.Priyavaakayam-Speaking what is pleasing.
5.Kurror Seva-Serving the elders.
6.Dhrudam cha Eva vrtham Krutham-if one takes a vow, it has to be completed.