Let's break it down. There are 4 variables in the expression for $allowDownload and 5 conditions under which the download is allowed. As soon as one condition is met, there is no need to evaluate any of the others.

The variables are:
- $args['downloadOwnDataOnly'] Set when editing the form, it is stated 'If ticked then the user is only allowed to download data when showing just their own data.'

- $reportOptions['extraParams']['ownData'] Set when editing the form by adding a value for ownData in the list of preset parameter values. If set to 1 the form will only ever return own data.

- $_POST['explore-ownData'] If there was no preset parameter value the user is asked if they want to see all data or own data. This is their response: '1' for ownData

- $reportOptions['paramDefaults']['ownData'] Set when editing the form by adding a value for ownData in the list of default parameter values. This allows the report to run initially but can be overridden subsequently.

The five conditions when downloads are allowed are
1. If the downloadOwnDataOnly setting has no value.

!isset($args['downloadOwnDataOnly'])

Probably for backwards compatibility with versions of this form created prior to the existence of this setting when downloads were always allowed.

2. If the downloadOwnDataOnly setting is false.

!$args['downloadOwnDataOnly'] 

Downloads are enabled for all users.

3. The ownData report parameter has been preset to true

isset($reportOptions['extraParams']['ownData']) && $reportOptions['extraParams']['ownData']===1

Since the first two conditions must have been false we can only download own data but, if this preset is true, we will only ever request ownData and thus download is permitted.

4. The user has requested ownData.

isset($_POST['explore-ownData']) && $_POST['explore-ownData']==='1'

We can only download own data and the user has requested own data.

5. On first running the report when the user has not supplied a value for ownData but the default value is true.

(!(isset($_POST['explore-ownData']) || $_POST['explore-ownData']==='0') 
            && isset($reportOptions['paramDefaults']['ownData']) && $reportOptions['paramDefaults']['ownData']===1);

Okay, so condition 5 is the one that matters. $_POST['explore-ownData'] can be in one of three states, unset, true (1), or false (not 1 - usually 0 unless a hacker is playing games). If it is true, condition 4 will allow download. If it is false there should be no download so I think this condition only needs to apply when it is unset.

I have also found that $reportOptions['extraParams']['ownData'] and $reportOptions['paramDefaults']['ownData'] return string values so comparing them exactly to integers is wrong. So, I propose to you the following.

$allowDownload = !isset($args['downloadOwnDataOnly']) 
    || !$args['downloadOwnDataOnly'] 
    || (isset($reportOptions['extraParams']['ownData']) && $reportOptions['extraParams']['ownData'] === '1')
    || (isset($_POST['explore-ownData']) && $_POST['explore-ownData'] === '1')
    || (!isset($_POST['explore-ownData']) 
            && isset($reportOptions['paramDefaults']['ownData']) && $reportOptions['paramDefaults']['ownData'] === '1');

Hi both
I think the logic is right. I wonder if this code should be rewritten with some variables for readability, e.g.

    $olOptions = iform_map_get_ol_options($args);
    $r .= map_helper::map_panel($options, $olOptions);
    $downloadOwnDataOnlyInArgs = isset($args['downloadOwnDataOnly']) && $args['downloadOwnDataOnly'];
    $ownDataValueInPost = isset($_POST['explore-ownData']);
    $exploreOwnDataEnabledInPost = $ownDataValueInPost && $_POST['explore-ownData']==='1';
    $reportParamPresetsSetToOwnData = isset($reportOptions['extraParams']['ownData']) && $reportOptions['extraParams']['ownData']==='1';
    $reportParamDefautsSetToOwnData = isset($reportOptions['paramDefaults']['ownData']) && $reportOptions['paramDefaults']['ownData']==='1';
    $allowDownload = !$downloadOwnDataOnlyInArgs 
      || $reportParamPresetsSetToOwnData
      || $exploreOwnDataEnabledInPost
      || (!$ownDataValueInPost && $reportParamDefautsSetToOwnData);
    $reportOptions = array_merge(
        $reportOptions,
        array(
          'id'=>'explore-records',
          'paramsOnly'=>false,
          'autoParamsForm'=>false,
          'downloadLink'=>$allowDownload,
          'rowClass'=>'certainty{certainty}'
        )
    );

Cheers
John