Generate the answer for a given question. The question requires common knowledge of English. Make sure that the answer is in detail, long, consistent with the context, and requires general knowledge of English. To be less repetitive, please vary your language for each question. Give a proper explanation to answer, and if necessary, provide the definition of various terms. And conclude your answer if it's long. If you have used other resources (e.g., Merriam Webster's.) to answer the question, include citations in your answer. You don't need to paraphrase the context of your resources, but make sure that your answer is consistent and complete.

This is similar to a palindrome but, instead of a word/sentence that reads the same forwards and backward, is there a word for words/sentences that read the same right side up and upside-down? See picture below where the word 'yeah' is written in cursive:.
That is called an ambigram. It is a typographical design that can be read in more than one direction. ambigram noun A typographical design consisting of text modified in such a way that it can be read in multiple orientations, as in mirror image, inverted, or when rotated. (ODO) Famously (?) used in Dan Brown's Angels and Demons.

Possible Duplicate: Do you use 'a' or 'an' before acronyms? Does one use 'a' or 'an' before the word 'X-Ray'? Quite simply, should a sentence read 'a XML report' or 'an XML report'?.
It's 'an XML report', because which form of the indefinite article to use is decided by how the next word is pronounced. In this case, it's pronounced: An ex-emm-ell report 'XML' begins with a vowel sound, 'e', so an is used rather than a.

In the morning of 19 April 2016, Taliban militants attacked a security team. Or On the morning of 19 April 2016, Taliban militants attacked a security team .
'on' is the correct preposition and 'in' is the incorrect one for this case. 'The morning of' functions as an adjectival phrase clarifying the specific time and date 'on 19 April 2016'. 'On' is used because it belongs to the date here, specific part of the day. The normal language constructions would be: on + date (with the year or without it) or day of the week in + morning, afternoon, evening (in the morning, in the evening) But, when we talk about a specific morning, afternoon, or when we describe the part of the day it should be used with on: on the morning of [date], You can't say 'I will see you on the morning' - it's incorrect. In or on? We use in with morning, afternoon, evening and night, but we use on when we talk about a specific morning, afternoon, etc., or when we describe the part of the day.