Getting EMC Unity array API types' definitions from API itself

ExampleSnippetsForGettingAPITypeDefs.ps1

## URI is to just get the "types" info
$tmpUri = "https://someunity.dom.com/api/types"
## this example uses the websession and headers from already having established connection to Unity API (as perfomed by Connect-Unity cmdlet from "Unity-PowerShell" PS module)
$oWebResponse = Invoke-WebRequest -Uri $tmpURI -ContentType "application/json" -Websession $Session.Websession -Headers $session.headers -Method GET

## the ".entries" property has the collection of types data
## there are about 422 objects returned in ".entries" property on this 600F (about half of which are Enum types)
($oWebResponse.content | ConvertFrom-Json).entries
# @base                                  updated                    links
# -----                                  -------                    -----
# https://someunity.dom.com/api/types   2017-03-03T14:19:11.799Z   {@{rel=self; href=/ACEAccessLevelEnum}}
# https://someunity.dom.com/api/types   2017-03-03T14:19:11.799Z   {@{rel=self; href=/ACEAccessTypeEnum}}
# https://someunity.dom.com/api/types   2017-03-03T14:19:11.799Z   {@{rel=self; href=/AccessPolicyEnum}}
# https://someunity.dom.com/api/types   2017-03-03T14:19:11.799Z   {@{rel=self; href=/AllocationStatusEnum}}
# ...

## some member info for the entries
($oWebResponse.content | ConvertFrom-Json).entries | Get-Member

#    TypeName: System.Management.Automation.PSCustomObject

# Name        MemberType   Definition
# ----        ----------   ----------
# Equals      Method       bool Equals(System.Object obj)
# GetHashCode Method       int GetHashCode()
# GetType     Method       type GetType()
# ToString    Method       string ToString()
# @base       NoteProperty string @base=https://someunity.dom.com/api/types
# content     NoteProperty System.Management.Automation.PSCustomObject content=@{name=ACEAccessLevelEnum...
# links       NoteProperty Object[] links=System.Object[]
# updated     NoteProperty string updated=2017-03-03T14:19:11.799Z


## getting the "attributes" property of a LUN entry (LUN object type definition, essentially)
(($oWebResponse.content | ConvertFrom-Json).entries | Where-Object {$_.content.name -eq "lun"}).content.attributes | sort name

# name                     type                  description
# ----                     ----                  -----------
# compressionPercent       Integer               Percent compression rate
# compressionRatio         Float                 compression ratio
# compressionSizeSaved     Integer               Storage element saved space by inline compression
# currentNode              NodeEnum              The storage processor that is the current owner of this LUN.
# defaultNode              NodeEnum              The storage processor that is the default owner of this LUN.
# description              String                Description of the LUN.
# health                   health                Health information for the LUN, as defined by the health resource typ...
# hostAccess               List<blockHostAccess> Host access permissions for the LUN.
# id                       String                Unique identifier of the LUN.
# ioLimitPolicy            ioLimitPolicy         I/O limit policy that applies to the LUN, as defined by the ioLimitPo...
# isCompressionEnabled     Boolean               True if compression is enabled
# isReplicationDestination Boolean               Indicates whether the LUN is a replication destination. Valid values ...
# isSnapSchedulePaused     Boolean               (Applies if the LUN has an associated snap schedule.) Indicates wheth...
# isThinEnabled            Boolean               Indicates whether thin provisioning is enabled. <ul> <li>true - The L...
# metadataSize             Integer               Size of the LUN metadata.
# metadataSizeAllocated    Integer               Size of pool space allocated for the LUN's metadata.
# moveSession              moveSession           The moveSession associated with the current lun
# name                     String                Name of the LUN.
# perTierSizeUsed          List<Integer>         Sizes of space allocations by the LUN on the tiers of multi-tier stor...
# pool                     pool                  The pool in which the LUN is allocated.
# sizeAllocated            Integer               Size of space actually allocated in the pool for the LUN: <ul> <li>Fo...
# sizeTotal                Integer               LUN size that the system presents to the host or end user.
# sizeUsed                 Integer               Used size is not applicable to LUN and this value is not set.
# snapCount                Integer               Number of snapshots of the LUN.
# snapSchedule             snapSchedule          Snapshot schedule for the LUN, as defined by the snapSchedule. This v...
# snapsSize                Integer               Size of the LUN snapshots.
# snapsSizeAllocated       Integer               Size of pool space allocated for snapshots of the LUN.
# snapWwn                  String                World Wide Name of the Snap Mount Point.
# storageResource          storageResource       The storage resource with which LUN is associated.
# type                     LUNTypeEnum           Type of the LUN.
# wwn                      String                The world wide name of the LUN.

Thanks for the tips !!!
FYI you can use function Get-UnityItem to query a specific item.

$Session = Connect-Unity -Server 'someunity.dom.com'
$tmpUri = "/api/types"
$oWebResponse = Get-UnityItem -Session $Session -Uri $tmpUri

Yessirree. And, good to know about Get-UnityItem, thanks -- that will definitely be handy for exploring.