(ViT) PatchEmbeddingBlock.pos_embed has conv and perceptron options?

[asy51]

What are these conv and perceptron options? They affect the arrangement of PatchEmbeddingBlock.patch_embeddings, but the how and why are not clear to me.

MONAI/monai/networks/blocks/patchembedding.py

Lines 86 to 98 in 00a6434

	if self.pos_embed == "conv":
	self.patch_embeddings = Conv[Conv.CONV, spatial_dims](
	in_channels=in_channels, out_channels=hidden_size, kernel_size=patch_size, stride=patch_size
	)
	elif self.pos_embed == "perceptron":
	# for 3d: "b c (h p1) (w p2) (d p3)-> b (h w d) (p1 p2 p3 c)"
	chars = (("h", "p1"), ("w", "p2"), ("d", "p3"))[:spatial_dims]
	from_chars = "b c " + " ".join(f"({k} {v})" for k, v in chars)
	to_chars = f"b ({' '.join([c[0] for c in chars])}) ({' '.join([c[1] for c in chars])} c)"
	axes_len = {f"p{i+1}": p for i, p in enumerate(patch_size)}
	self.patch_embeddings = nn.Sequential(
	Rearrange(f"{from_chars} -> {to_chars}", **axes_len), nn.Linear(self.patch_dim, hidden_size)
	)

I will look into this myself and give an update here, but wanted to see if anyone could shed some light on it.
Thank you!