qualified sequence feature or collection qualified sequence feature A sequence feature whose identity is additionally dependent on the context or state of the material sequence molecule in which the feature is concretized. This context/state describes factors external to the feature's intrinsic sequence and position that can influences its expression, such as being targeted by gene-knockdown reagents, or an epigenetic modification. Modeling sequence entities at this 'qualified' level is useful for distinguishing cases where features with identical sequence and position as separate instances - based on their material bearers being found in different contexts. For example, consider a situation where the zebrafish shha gene (a sequence feature) is targeted in two experimental groups of fish by two different morpholinos, and phenotypes are assessed for each. We want to be able to represent two 'variants' of the shha gene in this scenario as separate 'qualified sequence feature' instances so we can capture data about the phenotypes resulting from each - just as we would separately represent to different sequence variants (alleles) of the shha gene at the sequence feature level so that we can track their associated phenotypes. Consider wild-type zebrafish shha gene in the context of being targeted by morpholino MO-1 vs morpholino MO-2 in separate experiments. These shha genes share identical sequence and position, but represent distinct instances of a 'qualified sequence feature' because of their different external contexts. This is important because these qualified features could have distinct phenotypes associated with them (just as two different sequence variants (alleles) of the same gene can have potentially different associated phenotypes). GENO defines three levels of sequence-related artifacts, which are distinguished by their identity criteria. 1. 'Biological sequence' identity is dependent only on the ordering of units that comprise the sequence. 2. 'Sequence feature' identity is dependent on its sequence and the genomic location of the sequence (this is consistent with the definition of 'sequence feature' in the Sequence Ontology). 3. 'Qualified sequence feature' identity is additionally dependent on some aspect of the physical state or context of the genetic material in which the feature is concretized. This third criteria is extrinsic to its sequence and its genomic location. For example, the feature's physical concretization being targeted by a gene knockdown reagent in a cell (e.g. the zebrafish Shha gene as targeted by the morpholino 'Shha-MO1'), or its being transiently expressed from a recombinant expression construct (e.g. the human SHH gene as expressed in a mouse Shh knock-out cell line), or its having been epigenetically modified in a way that alters its expression level or pattern (e.g. the human SHH gene with a specific methylation pattern).