To arrange that the location information normally given on the left-hand side of the status line appears in block capitals.

Not much is needed for this. The only noteworthy point is that it doesn't work by changing the LHSL to "[the player's surroundings in upper case]": it cannot do this because "the player's surroundings" is not a value. Instead, "[the player's surroundings]" is a text substitution sometimes printing the name of a room, sometimes printing "Darkness", and so on. We must therefore load it into a text first, and then apply "…in upper case".

"Capital City"
Capital City is a room. East is Lower Caissons. South of Lower Caissons
is San Seriffe. East of San Seriffe is a dark room.
To say the player's capitalised surroundings:
   let the masthead be "[the player's surroundings]" in upper case;
   say the masthead.
When play begins:
   now the left hand status line is "[the player's capitalised surroundings]".
Test me with "e / s / e".
Test me with "e / s / e".
Capital City

>(Testing.)

>[1] e

Lower Caissons

>[2] s

San Seriffe

>[3] e

Darkness
It is pitch dark, and you can't see a thing.