## 4 SERS Requirements
### Recommendation Model
\begin{table}
\begin{tabular}{|p{56.9 pt}|p{56.9 pt}|p{56.9 pt}|p{56.9 pt}|} \hline Element & Attribute & Standards/Sures. & Usage of the Standard/Sustification by Attribute \\ \hline \multirow{8}{*}{type} & \multirow{8}{*}{object} & \multirow{8}{*}{IMS-LD, IMS-QTI, SCORM, IMS-CP} & The object attribute refers to the resource element in IMS-LD or SCORM. In IMS-LD the resource element refers not only to content but also to other facilities such as the conference functionality. IMS-QTI describes a particular type of test item, and thus, describes a specific object type. Content resources can be packed with their metadata with IMS-CP. \\ \cline{2-4}  & \multirow{2}{*}{action} & \multirow{2}{*}{IMS-LD, SCORM} & The activity element in IMS-LD and SCORM provide the instructions of what to do on the resource (\(\mathit{i.e.}\), the object). \\ \hline \multirow{8}{*}{content} & \multirow{8}{*}{text} & \multirow{8}{*}{W3C WCAG} & The text should consider the WCAG 2.0 guideline “3.1 Readable”, which points to making text content readable and understandable. \\ \cline{2-4}  & \multirow{2}{*}{link} & \multirow{2}{*}{W3C WCAG} & The link and the and its title relates to WCAG 2.0 guideline “2.4 Navigable”, which points to providing ways to help users navigate, find content, and determine where they are. \\ \hline \multirow{8}{*}{runtime information} & \multirow{8}{*}{restrictions applicability conditions} & IEEE-LOM, IMS-AfA, IMS-LD, IMS-LIP, IMS-MD, ISO/IEC 24751, SCORM,W3C CC/PP & For both the restrictions and the applicability conditions (\(\mathit{i.e.}\), the runtime information element in the recommendation model) metadata that characterizes the context of the recommendation is needed. This information can involve the description of user features (in terms of IMS-LIP, IMS AfA or ISO/IEC 24751), resources (IEEE-LOM, IMS-AfA, IMS-MD, ISO/IED 24751), conditions on properties among the resources (IMS-LD, SCORM) or device capabilities (W3C CC/PP). \\ \cline{2-4}  & \multirow{2}{*}{rationale} & \multirow{2}{*}{IMS-RDCEO} & IMS-RDCEO can be used to facilitate the description of the competence addressed by the recommendation as it defines and structure of these competences, including a human readable description of the competency. \\ \cline{2-4}  & \multirow{2}{*}{explanation} & \multirow{2}{*}{W3C WCAG} & The explanation should consider WCAG 2.0 guideline “3.1 Readable”, which points to making text content readable and understandable. \\ \hline \multirow{2}{*}{semantic information} & category & \multirow{2}{*}{not available} & Currently there is no standard or specification available that can support the description of these attributes, as they are very much dependant on the recommendation nature. \\ \cline{2-4}  & \multirow{2}{*}{stage} & \multirow{2}{*}{not available} & Currently there is no standard or specification available that can support the description of these attributes, as they are very much dependant on the recommendation nature. \\ \cline{2-4}  & & & \\ \hline \end{tabular}
\end{table} 
Table 4: Standards and specification that can be considered by the recommendation model attributes. Table 4 shows that several standards and specifications exist that provide descriptions for the type and runtime information attributes. However, this mapping is not straight forward, as has already been acknowledged in literature; there are still some aspects for which different specifications overlap, while there are other aspects for which there are as yet no defined specifications [17]. The content attributes should follow the W3C WGAG to make the information accessible to the users. For the justification element, both the educational view (_i.e._, IMS-RDCEO) and the accessibility view (W3C WCAG) are to be considered. Finally, for the semantic information attributes (_i.e._, category, stage, origin and relevance) there is currently no standard or specification available that can support their description, as they are very much dependant on the recommendation nature.