The original Selmer guitars suffered from a weak point on their top at the neck joint, and the sound hole area. The top plate and braces were not strong enough which allowed the neck angle to shift under string tension, causing the action to rise up. Over the years some of them have had their bridges adjusted very low to compensate for that.
To alleviate that problem, the top bracing is intentionally stronger in that area on AJL-guitars. The tops plates are also carefully hand-shaped with an undulating thickness which adds structural stability to the area around the sound hole and neck joint while enabling the vibration area to remain very thin and responsive.
Gypsyguitars have their tops bent on arched top braces. Some of the original Selmers had the top with round bent, some of them had the bend made with heat, French call that angle ”pliage” steeper visible angle behind the bridge on their tops.
Also AJL Selmer/Maccaferri-style guitars have that "pliage".