Is ERC-20 Ethereum mainnet?

Is ERC-20 truly considered as part of the Ethereum mainnet? This question seems to delve into the technicalities of blockchain technology, specifically within the realm of Ethereum. ERC-20, as we know, is a technical standard used for smart contracts on the Ethereum blockchain for implementing tokens. But does this automatically classify it as being a part of the mainnet? The Ethereum mainnet, on the other hand, refers to the primary, operational network where transactions and smart contracts are executed. So, are ERC-20 tokens simply compliant with the standards set by Ethereum, or do they actually reside on the mainnet itself? It's a subtle but important distinction that I'd like to clarify.