Brown's Signalling, 18th Edition, February, 1916, pages 192-198:

Questions  and  Answers.

Q.1.--How many Flags are there in the New International Code of Signals?
A.--There are 2 Burgees, 5 Pennants, and 19 Square Flags--in all 26, giving 1 Flag for each Letter in the Alphabet, and a Code Flag or Answering Pennant.
Q.2.--Describe the parts of a Flag.
A.--The side next the Flagstaff is termed the Hoist, and the Top or Outer Edge the Fly.
    Note.--The Flags of the New International Code would be recognised whether they were hoisted either side up. The difference on Flags L, N, O, U, Y, and Z, in this way would not interfere with the Signal. There are however several Foreign and British Flags which alter their meaning as well as betokening disrespect when hoisted wrong side up--vide: The British Red Ensign hoisted with the Union down is generally understood to mean "Danger; want Assistance," etc., though it is not a Code Signal, or not an authorised signal of distress.
Q.3.--What is the Code Signal Pennant for?
A.--When a Signal is to be made by the International Code, this Pennant is hoisted under the Ensign at the Peak to indicate that the Signal to be given is taken from the International Code.
Q.4.--In Signalling a Ship or a Signal Station what do you do first?
A.--Hoist the National Ensign, with Code Flag under.
Q.5.--And what do you do next?
A.--On observing that my Signal is observed, which is done by the ship or station hoisting the Answering Pennant "close up," I then proceed to give ship's Distinguishing Signal--Where from? Where bound to? Number of days out? and any other signal which may be required.
Q.6.--When you have hoisted the Code Signal, what do you do?
A.--Wait for the Signal from the other Ship or from a Signal Station, and keep the Code Flag flying till answered, which should be the Code Flag used as the Answering Pennant run up to the Masthead or where best seen.
Q.7.--If your signal is understood, what do you do?
A.--Hoist the signal I wish to make where best seen, which is generally at the Foremast Head.
Q.8.--If you do not understand a Signal made for your ship, what are you required to do?
A.--I keep my Answering Pennant at the dip, and wait till the signal is repeated or altered, and when understood I then hoist the Answering Pennant close up.
Q.9.--How could you find quickly what Flags to hoist for a General Signal you wish to make?
A.--I would open the Signal Book at the centre, and glance down the indiced leaves under the initial letters, for the initial letter of the most important (or chief word) in the signal I wish to make, such as "Cargo," "Boat," "Damage," then by opening the book at that place and finding the chief word, the signal will be found under it, with the flags to hoist for it.
Q.10.--How many One-Flag Signals are there?
A.--Twenty-Six. They are made by Hand, on board vessels towing and being towed, and are only shown just above the gunwale.
Q.11.--What Flags, when they are flown singly, have distinctive meanings?
A.--The Burgees A and B, Pennants C and D, and Flags L and P and S have distinctive meanings when flown singly.
    In Alphabetical Signalling, or Numeral Table Signalling, hoists of 1, 2, 3, or 4 Flags may be hoisted, but no other hoist of One Flag is in the Code except with the addition of the Code Flag.
Q.12.--How can you distinguish a British Pilot Vessel in the day time?
A.--She flies at the masthead a flag the upper horizontal half of which is white and the lower half red.
Q.13.--Is the Code Pennant used for any other purpose?
A.--It is used principally as the "Code Signal" or "Answering Pennant." It is also used
With hoists of  Urgent Signals, Code Flag being over any One Flag.
Do.Latitude Signals, Code Flag being over any Two Flags.
Do.Longitude Signals, Code Flag being over any Two Flags.
Do.Division of Time Signals (H.M.S.), Code Flag being over any Two Flags.
Do.Barometer Signals, Code Flag being over any Two Flags.
Do.Thermometer Signals, Code Flag being over any Two Flags.
Do.Numeral Signals, Code Flag being under any Two Flags.
Q.14.--Suppose you want to signal the name of a place?
A.--I would turn to the Geographical Signals arranged in alphabetical order.
Q.15.--If a General Signal is hoisted in reply, how would you find its meaning?
A.--I would open the book at centre, follow the indiced edges under initial letter where to open it, then on finding the signal letters I could at once find their meaning opposite.
Q.16.--Suppose it was a Geographical Signal?
A.--I should turn to Geographical Signals where the flags are arranged in geographical order, and then I could find it at once.
Q.17.--How do you know a Geographical Signal?
A.--By any 4 Flag Signal with Flag A or B at top.
Q.18.--How do you know a Compass Signal?
A.--It is a 3 Flag Signal with Flag A at top.
Q.19.--How do you know an Urgent Signal?
A.--It is either 2 Flags of any letters, or 1 Flag with the Code Pennant over it. Urgent Signals are easily distinguished as they are all 2 Flag Signals, and are shown without any preparative signal.
Q.20.--Under what kind of Signal is Latitude, Longitude, Time, Barometer and Thermometer made?
A.--The Code Flag in all these Signals is hoisted over 2 Flags.
Q.21.--And when a Numeral Signal is required to be made--what is the form of Signal?
A.--The Code Flag is under any 2 Flags from UA to ZY.
Q.22.--How many Flags are allowed to form a hoist?
A.--Forms of hoist are arranged having 2, 3, and 4 Flags, and under certain conditions 1 Flag can form a hoist, but not more than 4 Flags in any one hoist.
Q.23--How do you know a General Signal?
A.--It is formed of 3 Flags with any flag uppermost from CXA to end of alphabetical rendering.
Q.24.--What Flags are in a ship's Distinguishing Signal?
A.--Any 4 Flags having Flag H or any succeeding letter of alphabet at top.
Q.25.--How do you know when a Man-of~War is signalling her name?
A.--It would be a 4 Flag hoist with Pennant G at top.
Q.26.--You intend to use the Alphabetical Signals, what Flag do you hoist?
A.--Before beginning Signal, I hoist Code Flag over E, it being Alphabetical Signal No. 1 as preliminary, and afterwards make hoists of 3 or 4 Flags representing the letters required till the word is formed.
Q.27.--And when you have made the Word?
A.--I hoist Code Flag over F, to signify a Dot after the Word or Initial.
Q.28.--And when the Alphabetical Signal is complete?
A.--I hoist Code Flag over G to indicate that the Alphabetical Signals are ended.
Q.29.--How many Flags can be in the Alphabetical Signals?
A.--1, 2, 3 or 4 as required.
Q.30.--Is there any special place for the Code Flag when you intend to communicate by the International Code?
A.--Yes, it must be hoisted under the National Ensign.
Q.31.--How do you distinguish between the Code Flag and the Answering Pennant?
A.--There is no difference as regards form or colour, only as the Code Signal it must be hoisted under the Ensign, and as the Answering Pennant it is hoisted singly where best seen.
Q.32.--Can you communicate with foreign ships by the Code?
A.--Commnunications can be signalled provided the foreign ship represented is in possession of a Code Book in their own language, or if they could use the British edition.
Q.33.--How do you recognise a Special Distant Signal?
A.--It is made by a single hoist followed by the Stop.
Q.34.--Are Distant Signals only made by the system of Square Flag, Pennant, Ball and Wheft?
A.--No. Distant Signals can either be made by the Fixed Semaphore, by means of shapes, as the Balls, Drum and Cones, or by the Square Flag, Pennant, Ball and Wheft.
Q.35.--Why are Distant Signals by Shapes preferred?
A.--Because they are when visible, independent of wind, as Flags are not, for their exhibition.
Q.36.--As to Distant Signals how are they deciphered?
A.--Each hoist only indicates one letter, and the combination of these gives the signal, read in the usual way same as flags: thus--YHU by Semaphore, or by Shapes, or by Flag, Pennant, Ball and Wheft the meaning is "Do you understand?" Each complete signal is required to be shown that it is completed.
Q.37.--What is a Wheft?
A.--It is any Flag either Square or Pennant shape, tied in the centre.
Q.38.--What is the character of the Distant Signal by Shape?
The characteristic of the Distant Signal is the Ball, 1 Ball at least appearing in every hoist, the signals from A to G having the Cone point upwards at top, or its equivalent in the Semaphore,as    1
Those from H to U having the Ball or Balls at top, or its equivalent in the Semaphore,as    2
Those from V to Z having the Cone point down at top, or its equivalent in the Semaphore,as    3
And the Special Signs i.e., "Code Flag," "Alphabetical," "Numeral," and "Finishing" Signs, by having the Drum at top, or its equivalent in the Semaphore,as    4
Q.39.--How many Special Distant Signals are there?
A.--There are thirty-seven, explained by numbers arranged in numerical order.
Q.40.--How are the Special Distant Signals read?
A.--They are read as figures, and reference is made to the Special Distant Signal Table, in their numerical order.
Q.41.--In making or reading a Signal of 2, 3, or 4 Flags, how do you proceed to note the Flags so as to get this meaning?
A.--The upper Flag is noted first, the others in succession downwards. The same applies to Semaphore or Distant Signals.