Short answers, pulled from the story.
Switzerland submitted its Intended Nationally Determined Contribution on the 27th of February 2015. This submission marked the country as the first nation to file such a document under international climate agreements.
The term INDC described initial contributions before the Paris Agreement took full effect, while NDC emerged after the agreement entered into force during 2016. Countries converted their INDCs into formal NDCs upon ratification unless they chose to submit fresh targets immediately.
Nations must update their national plans every five years according to Article 4 of the Paris Agreement. This cycle ensures periodic revisions reflect changing circumstances or increased ambitions for emission reductions.
Resource constraints hinder developing nations from implementing necessary policies effectively and limit their ability to secure high-level political support within governments. India requires at least 2.5 trillion US dollars to achieve its 2015 through 2030 goals due to these financial barriers.
Eighty-five percent of surveyed countries reported challenges due to short timeframes available for development as of the 31st of March 2020. Less than one quarter received international support to prepare these initial documents while more than a quarter indicated they were still applying for assistance.