What is meant by "technology dependent" PHYs? Is there something like "technology independent" PHYs? To add the context as Zac67 correctly mentioned, I was reading clause 73 of 802.3-2015. 73.3 - Functional specifications. Excerpt: "The Auto-Negotiation functions shall interact with the technology-dependent PHYs through the Technology-Dependent interface (see 73.9). Technology-Dependent PHYs include 1000BASE-KX, ..."

Without context, this isn't easy to answer. Most probably, this refers to modular PHYs like SFP, SFP+, QSFP, CFP that can be upgraded as technology advances. For instance you could buy an SFP+ port device and when technology advanced get a 10GBASE-ZR PHY for it that wasn't available from the start - not a speed but a reach upgrade. Or replace one 1000BASE-LX SFP with two 1000BASE-BX SFPs for the same fiber, increasing the (aggregated) bandwidth.

EDIT with context of _Clause 73. Auto-Negotiation for backplane and copper cable assembly_ :

73.9: "The Technology-Dependent interface is the communication mechanism between each technology’s PCS and the Auto-Negotiation function."

"Technology-dependent" in this context in conjunction with auto-negotiation means something in the line of PHY generation and its downward compatibility. A 10GBASE-T PHY should be able to link down to a 1000BASE-T PHY and so on.

"Technology- _in_ dependent" in this context makes no sense.