Throughout the game, both players have a bishop drop threat, with which they can exploit any positional weakness that their opponent inadvertently creates.
This has a number of benefits: it gives White a pawn in hand that can be used to drop later in the game, and it frees up the rook so that it can move to any rank above Black's camp (see: Sabaki).
Both players move their left silver to the 77 and 33 squares (Black and White, respectively) in order to accomplish this goal in both Bishop Exchange and Fortress openings.
Since the bishop is off the board, the king is not restricted in rightward movement to the 69 square like the usual development in the Fortress opening.
The adjacent diagram shows an example of such a position from 2019 – a Double Reclining Silver, P25 R29 G48 Identical Formation variation.
[7] Right King is more commonly played by White but uncommon for Black in the regular Bishop Exchange opening.
Nonetheless, this 1.P-76 P-84 2.S-68 P-34 3.B-77 sequence is quite uncommon since Black usually moves their bishop to 77 this early only when White plays the forcing ...P-85 rook pawn push.
This defensive move is more flexible than 2...P-85 since 2...G-32 does not put pressure on Black to immediately decide on whether to prevent or allow the eighth file pawn exchange leaving the opening still fairly ambiguous.
And, Black's 3.G-78 response would also still allow for Bishop Exchange (2...G-32 3.G-78 P-85 4.B-77 P-34 5.S-88) and Side Pawn Capture or Double Wing Attack (2...G-32 3.G-78 P-34 4.P-25 P-85 5.P-24 or 2...G-32 3.G-78 P-85 4.P-25 P-86 or 2...G-32 3.P-25 P-85 4.P-24 Px24 5.Rx24 P*23 6.R-26 P-86) openings.
Nonetheless, although currently not as popular, some professional players have played these positions 2015–2019 aiming for the new P-25 G-48 R-29 Reclining Silver formation.
[18][19] Another feature of 3.P-25 is that it prevents White from playing Snowroof after declining the Bishop Exchange lines, which has become more popular after 2016.
This delay of advancing their rook pawn in favor of an immediate defense of the eighth file is known as 飛車先保留 (hisha saki ryūgata) in Japanese.
[8] Finally, keeping a pawn on 26 prevents White from dropping a bishop to that square, which could be a possible counterattack should Black's rook leave the second file.
Of course, Black can play P-25 anytime later in the game if desired (which may end up making the delayed rook push merely a transposition of some lines with the early 3.P-25).
One consequence of playing 2.B-77 is that without Black's pressuring P-25 White can decline Bishop Exchange and choose a Snowroof opening.
Therefore, defending the bishop with the silver is important for the defense of the eighth file (as preventing rook pawn exchanges is one of the main points of this opening).
If Black aims for a Fortress castle, then 4.S-78 is often not chosen as placing the silver on the seventh file prevents G-78 for a few moves.
Note that if Black follows with the early 5.P-25 after 4...G-32, then White will no longer be able to decline Bishop Exchange to play Snowroof or Yagura.
Black recaptures with the silver maintaining defense of the 86 square (preventing White's pawn exchange).
Although Black has the possibility of recapturing White's 5...Bx77+ with 6.Gx77, professional thought is that having the left gold on the 77 square is a bad shape.
This move contributes to White's castle development and importantly prepares for ...S-33 to defend the 24 square (preventing the pawn exchange) should Black push P-25.
Although S-22 is the required move in the early 3.P-25 variation (so as not to block the rook's defense of the gold on 32), that is not true here since Black's pawn is still on the 26 square (so 7.P-25 is simply met with 7...S-33).
6...S-42 allows the silver defends more toward the center of White's camp compared with the peripheral ...S-22, which may be favorable when Black does not play P-25.
[6][25] The ...S-22 ...K-42 formation has been reevaluated as a good defense when Black's knight jumps early in the opening as is the case in some current developments.
If instead Black chooses another development such as 6.S-48, then White can construct their Fortress castle in the usual fashion with 6...S-42 meeting 7.P-25 with 7...S-33.
However, Yasuhiro Masuda suggests that these are difficult lines and recommends 6...B-33 in spite of the fact that computer shogi engines often play 6...S-42.
Since Fortress requires many moves to construct, Black needs to wary that White may attack first.
In Classic Bishop Exchange openings, the natural move after White's P-85 was to likewise advance Black's rook pawn.
However, the rook pawn push at this early juncture began to become disfavored by many professional shogi players since it slows down development of other pieces and eliminates a possible knight jump to the 85 square, which might be used in the Reclining Silver variations, which have become more popular than compared with Bishop Exchange games played before the 1980s.
If Black does not respond to this configuration now, White can reject a Bishop Exchange opening with their next move by moving the silver up to 33 where it forms the initial construction of a Fortress castle leading to White's likely Fortress opening where an early bishop trade is no longer possible.