This new feature aims at pushing input values and a set of output values onto the stack, thereby expanding the capabilities of Bitcoin scripting. Detailed information regarding this proposal can be found in the draft of the Bitcoin Improvement Proposal (BIP), accessible here, and its implementation is documented in a GitHub repository. The initiative seeks to integrate this feature with a 64bit op code, as discussed in a pull request (PR) and further elaborated on Delving Bitcoin.

A key aspect of the proposed OP_INOUT_AMOUNT involves addressing the current limitations surrounding the verification process by the Script interpreter. Currently, only the input and output amounts at the index being verified are pushed, leading to discussions on whether extending the capability to verify beyond the immediate input and output at the current index could offer more sophisticated transaction handling, akin to the functionalities offered by SIGHASH flags. Community feedback is encouraged to delve into potential improvements and explore the feasibility of such enhancements.

From a technical perspective, changes have been proposed to the BaseTransactionSignatureChecker, introducing two novel methods: GetNIn() and GetTransactionData(). These methods aim to identify the input index under verification and provide access to relevant transaction data, respectively. Although these additions offer a convenient solution, they prompt considerations regarding their structural placement within the Bitcoin framework, suggesting that a reevaluation might be necessary to optimally incorporate these functionalities.

The overarching goal of these developments is to support future advancements, specifically the implementation of [OP_TLUV](https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2021-September/019419.html). This ambition highlights a broader vision for leveraging innovative features to enhance the Bitcoin ecosystem, signaling a commitment to continuous improvement and adaptation in response to evolving needs and possibilities within the digital currency landscape.