I have accessed the Australian War Memorial website for this question and their interpretation on the Last Post, the One Minute Silence, and finally the Rouse and Reveille is interpreted in the Australian context. I know it is a bit wordy but .......
In military tradition, the Last Post is the bugle call that signifies the end of the day's activities. It is also sounded at military funerals and commemorative services such as ANZAC Day and Remembrance Day to indicate that the soldier has gone to his final rest.
The Last Post is one of a number of bugle calls in military tradition that mark the phases of the day. While Reveille signaled the start of a soldier's day, the Last Post signaled its end. The call is believed originally to have been part of a more elaborate routine, known in the British Army as "tattoo", that had its origins in the 17th century. In the evening, a duty officer had to do the rounds of his unit's position, checking that the sentry posts were manned and rounding up the off-duty soldiers and packing them off to their beds or billets. He would be accompanied by one or more musicians. The first post was sounded when the duty officer started his rounds and, as the party proceeded from post to post, a drum was played. The drum beats told off-duty soldiers it was time to rest; if the soldiers were billeted in a town, the beats told them it was time to quit the pubs. "Tattoo" is a derivation of doe den tap toe, Dutch for "turn off the taps", a call which is said to have followed the drum beats in Dutch pubs while British armies were campaigning through Holland and Flanders in the 1690s. (The American practice of "taps" or "drum taps" also originated from the routine.) Another bugle call was sounded when the party completed its rounds, reaching the "last post" – this signaled the night sentries were alert at their posts and gave one last warning to any soldiers still at large to retire for the evening.
The Last Post was eventually incorporated into funeral and memorial services as a final farewell, and symbolises the duty of the dead is over and they can rest in peace.
Silence for one or two minutes is included in the ANZAC Day ceremony as a sign of respect and a time for reflection. The idea for the two-minutes silence is said to have originated with Edward George Honey, a Melbourne journalist and First World War veteran who was living in London in 1919. He wrote a letter to the London Evening News in which he appealed for five-minutes silence, to honour the sacrifice of those who had died during the war. In October 1919 Sir Percy Fitzpatrick, a South African, suggested a period of silence on Armistice Day in all the countries of the empire. Fitzpatrick's idea had its origins in a period of silence that was observed at noon in Cape Town following heavy losses among the South African Brigade on the Western Front; this observance continued until the end of the war. Fitzpatrick's idea was presented to King George V, who readily agreed to the proposal. But after a trial with the Grenadier guards at Buckingham Palace, at which both Honey and Fitzpatrick were present, the period of silence was shortened to two minutes. The connection between Honey and Fitzpatrick, and their ideas, if any existed at all, is unclear. On 6 November 1919 the King sent a special message to the people of the Commonwealth:
I believe that my people in every part of the Empire fervently wish to perpetuate the memory of that Great Deliverance, and of those who laid down their lives to achieve it.The King continued to ask that "a complete suspension of all our normal activities" be observed for two minutes at "the eleventh hour of the eleventh day of the eleventh month" so that "in perfect stillness the thoughts of everyone may be concentrated on reverent remembrance of the Glorious Dead". Two-minutes silence was first observed in Australia on the first anniversary of the armistice and continues to be observed on Remembrance Day. The two-minutes silence has over the years been incorporated into ANZAC Day and other commemorative ceremonies. (This is now generally accepted and practiced as one minute of silence.)
However, after the one minute silence, flags are raised from half mast to the masthead as the Rouse is sounded. Today it is associated with the Last Post at all military funerals, and at services of dedication and remembrance.
Since Roman times, bugles or horns had been used as signals to command soldiers on the battlefield and to regulate soldiers' days in barracks. The Reveille was a bright, cheerful call to rouse soldiers from their slumber, ready for duty; the call has also been adopted to conclude funeral services and remembrance services. It symbolises an awakening in a better world for the dead and "rouses" the living, their respects paid to the memory of their comrades, back to duty. The Rouse is a shorter bugle call, which, as its name suggests, was also used to call soldiers to their duties. Due to its much shorter length, the Rouse is most commonly used in conjunction with the Last Post at remembrance services. The exception is the Dawn Service, when the Reveille is played.
For your interest you might like to try www.awm.gov.au/commemoration/