According to Webster’s “New Dictionary Of Media And Communications”:
“A short play or other performance presented before a principal production in the 19th and early 20th Centuries, Curtain Raisers were presented while latecomers arrived, before the curtain was raised on the major attraction.”
According to “Oxford Advanced Dictionary” :
“A thing that precedes a similar but larger or more important event.”
Kind of news deals with the upcoming event. For example, religious, seasonal or national days like Defence Day, freedom Day, Holi, Eid, Christmas or Basant. The newspaper writes about the arrangement and preparation of the event.
A simple, complete and compact knowledge is transferred to reader so far as reader can get the basic knowledge about it and enjoy on the basis of that knowledge.
Usually, past tense is used while writing a news but here future tense is used because it would be going to happen a day after or some day after.