This article explores the relationship between disciplinary knowledge and subject pedagogy, utilising Maton's Legitimation Code Theory (LCT). It suggests ways that LCT could help facilitate deeper communication both within and between subject communities, providing a conceptual framework that gets beneath empirical manifestations to identify epistemic and semantic principles that generate those modalities. LCT's potential to represent systematised concepts diagrammatically may also enable wider communication. Following this, a small-scale case study is presented exploring the nature of the knowledge in the core topic "Changing Places" in the new geography A-Level (UK). This argued that what could be understood as a mismatch of expectations and dispositions by teachers and students can be understood more fundamentally as a contradiction (a 'code clash') regarding what counts as the 'rules of the game' within geography. The article ends by outlining implications for school geography rooted in the logic of the knowledge being pedagogically preinscribed, that is, that different knowledges' distinct epistemologies have real implications for how that knowledge should be recontextualised, reproduced and evaluated. It concludes that the exam board's recontextualisation of this disciplinary knowledge is not merely a simpler interpretation; it is more significantly a different ideal 'knower' that is being nurtured and examined.