Clarify which task elements and workflows are singular and which can be specified multiple times.

[claymcleod]

There a quite few workflow and task elements that the specification appears to imply can only occur once but that the grammar allows multiple occurrences.

For example, take a look at the task elements:

• An input section appears to be referred to as a singular section.
• A private declaration appears to allow zero or more declarations.
• A command section appears to be referred to as a singular section.
• An output section appears to be referred to as a singular section.
• A runtime section appears to be referred to as a singular section.
• Both metadata and parameter metadata sections appear to be referred to a singular, respectively.

For what it's worth, every example I have seen appears to follow the above conventions.

Contrast that with the parser implementation, which I interpret as (paraphrasing): a task can contain one or more task elements. A task element is defined as a task_input section, a task_output section, a task_command section, a task_runtime section, a bound_decls section, a parameter_metasection, or a meta section. As such, it follows that these elements can be defined multiple times.

[patmagee]

@claymcleod this is a general limitation of the grammars/parsers. We did not want to enforce strict ordering of task/workflow elements which would be required to use the grammar to enforce a single occurrence

• Only one input block is allowed in a workflow / task and it can happen anywhere in task.
• Any number of private declarations are allowed, but you cannot have two of the same declarations
• Only one command block is allowed
• Only one outputs section is allowed per workflow/task
• Only one runtime Sections is allowed
• Only one meta/parmeter-meta is allowed per workflow/task

[jdidion]

Agree with Patrick - this is true at least for the ANTLR parser. But I support adding clarification to the spec.