Card: shape runs change more than one setting (similar parameter count)

README.md

@@ -9,11 +9,12 @@ tags:
 
 # Ablation checkpoints (~180M parameters, 2.5B-token budget)
 
-Checkpoints of single-factor ablation runs: four finished runs (final checkpoints) and four runs interrupted mid-training
-(intermediate checkpoints). Each run changes **one** factor of a common reference recipe
+Checkpoints from architecture and optimizer experiments: four finished runs (final checkpoints) and four runs
+interrupted mid-training (intermediate checkpoints). Each run is compared with a common reference recipe
 (16 layers × d_model 896 × 14 heads, RMSNorm, QK-norm, RoPE θ 500 000, value residual, SwiGLU, no biases,
 Muon lr 0.02 + AdamW lr 6e-4, warmup 500, constant lr, decay over the last 20 % to lr / 10; batch 128 × 4096 tokens;
-planned 4768 steps = 2.5B tokens; tokenizer: the 32 768-token tokenizer of Slayer1B).
+planned 4768 steps = 2.5B tokens; tokenizer: the 32 768-token tokenizer of Slayer1B). VR0 and MU2 change one setting; K12, K22 and GQA change the shape
+at a similar parameter count (K12 and K22: depth and width; GQA: KV-head count and depth, 18 rather than 16 layers).
 
 ## Finished runs (final checkpoint, step 4768)