Technical terms in Railway circulars

ab initio

From the beginning

ad hoc

A solution designed for a specific problem or task, non-generalizable

bona fide

In good faith. Implies sincere good intention regardless of outcome.

de facto

In practice but not necessarily ordained by law

de novo

From the beginning, afresh.

erratum

A correction of a book or article.

ex gratia

By favour. When something has been done ex gratia, it has been done voluntarily, out of kindness or grace. 

ex officio

By virtue of office or position; "by right of office

ex parte

From (by or for) one party. An ex parte decision is one decided by a judge without requiring all of the parties to the controversy to be present.

ibid

Term used to provide an endnote or footnote that was cited in the preceding endnote or footnote.

idem

Meaning something that has been mentioned previously;.

in situ

 In the original place, appropriate position, or natural arrangement.

in toto

Totally; entirely

inter alia

Among other things

inter se

Between or amongst themselves

ipso facto

By the fact itself. Certain phenomenon is a direct consequence,

mutatis mutandis

By changing those things which need to be changed" or  necessary corrections to be made, where necessary,

prima facie

At first appearance.

pro forma

Practices or documents that are done as a pure formality, perfunctory or seek to satisfy the minimum requirements or to conform to a convention or doctrine.

pro rata

In proportion

sub judice

Under judgment. It means that a particular case or matter is currently under trial.

suo moto

On its own motion.  It is used where a government agency acts on its own cognizance

vide

See or refer to

 vice versa

Conversely

viz