Step	Criterion	Quantitative Threshold	Cancer Type
1	Expression filtering	Remove snoRNAs with zero expression in all samples	NSCLC, HNSC
2	Identification of immune-related snoRNAs (partial correlation)	|r| > 0.2, nominal p < 0.05, empirical FDR < 0.25	NSCLC, HNSC
3	Identification of immune-related snoRNAs (GSEA)	q < 0.25, adjusted p < 0.05	NSCLC, HNSC
4	Final immune-related snoRNA set	Intersection of step 2 and step 3	NSCLC, HNSC
5	Correlation with immune infiltra-tion (TIMER)	|Spearman r| ≥ 0.3, p < 0.05 for any immune cell types	NSCLC, HNSC
6	Final subtyping snoRNA set	Intersection of step 4 and step 5	NSCLC: 46 genes; HNSC: 39 genes