These two patterns mirror each other, so this article covers both. It explains:<\/p>\n\n\n\n
- \n
- how each pattern creates an activity that is open-ended in practice,<\/li>\n\n\n\n
- why P6\u2019s standard filters don\u2019t catch them, and<\/li>\n\n\n\n
- how \u01b5\u00fcmmer detects, identifies and reports them.<\/li>\n<\/ol>\n\n\n\n
Case 1: No Finish-Side Successor<\/h2>\n\n\n\n
In Figure 1, Task D is a successor to Task C using a Finish-to-Start (FS) relationship and is a predecessor to Task F using a Start-to-Start (SS) relationship.<\/p>\n\n\n
\n![\"\"](\"https:\/\/i0.wp.com\/www.foxquestsystems.net\/foxblog\/wp-content\/uploads\/2026\/09\/nofss.png?fit=840%2C244&ssl=1\")
Figure 1<\/figcaption><\/figure>\n<\/div>\n\n\n Task D has both a predecessor and a successor activity, so it does not violate the \u201cNo Open Ends\u201d rule. Accordingly, the P6 Global filters \u201cActivities without Predecessors\u201d and \u201cActivities without Successors\u201d return no results.<\/p>\n\n\n\n
However, Task D\u2019s only successor is linked from its start<\/em>. No logic leaves Task D\u2019s finish, so the finish behaves as if it were open-ended.<\/p>\n\n\n\n
Increasing Task D\u2019s Original Duration (OD) and recalculating the schedule gives these results:<\/p>\n\n\n\n
- \n
- OD from 10 to 12 days:<\/strong> Task D\u2019s Total Float (TF) does not change.<\/li>\n\n\n\n
- OD of 17 to 22 days:<\/strong> Task D\u2019s TF value decreases, but Task F\u2019s start and finish dates do not change.<\/li>\n\n\n\n
- OD of 23 days or more:<\/strong> Task D becomes critical and finishes after 29-Nov-26. Task F and Finish Milestone G still show a finish of 29-Nov-26.<\/li>\n<\/ol>\n\n\n\n
You can\u2019t build a P6 filter that finds this condition because there are no options available to construct the specific query. \u01b5\u00fcmmer identifies this anomaly in Analysis Report #14, \u201cActivities with No Finish Side Successor,\u201d<\/strong> (Figure 2).<\/p>\n\n\n
\n![\"\"](\"https:\/\/i0.wp.com\/www.foxquestsystems.net\/foxblog\/wp-content\/uploads\/2026\/09\/rpt14-nfss.png?fit=980%2C270&ssl=1\")
Figure 2<\/figcaption><\/figure>\n<\/div>\n\n\n Case 2: No Start-Side Predecessor<\/h2>\n\n\n\n
In Figure 3, Task D is a successor to Task C using a Finish-to-Finish (FF) relationship with a 5-day lag and is a predecessor to Task F using a FS relationship.<\/p>\n\n\n
\n![\"\"](\"https:\/\/i0.wp.com\/www.foxquestsystems.net\/foxblog\/wp-content\/uploads\/2026\/09\/nossp.png?fit=840%2C244&ssl=1\")
Figure 3<\/figcaption><\/figure>\n<\/div>\n\n\n As in Case 1, Task D has both a predecessor and a successor, so P6\u2019s open-ends filters returns no results.<\/p>\n\n\n\n
However, Task D\u2019s only predecessor is linked to its finish<\/em>. No logic enters Task D\u2019s start, so the start behaves as if it were open-ended.<\/p>\n\n\n\n
Increasing Task D\u2019s OD and recalculating the schedule gives these results:<\/p>\n\n\n\n
- \n
- OD from 10 to 31 days:<\/strong> No dates or TF values change for Task D or any other activity.<\/li>\n\n\n\n
- OD of 32 to 41 days:<\/strong> Task D\u2019s TF value decreases, but no other activity\u2019s dates change.<\/li>\n\n\n\n
- OD of more than 42 days:<\/strong> Task D starts on the Data Date and becomes critical. Task F is affected; however, Start Milestone A and Tasks B and C keep their dates, and their TF value increases accordingly.<\/li>\n<\/ol>\n\n\n\n
You can\u2019t build a P6 filter that finds this condition because there are no options available to construct the specific query. \u01b5\u00fcmmer identifies this anomaly in Analysis Report #15, \u201cActivities with No Start Side Predecessor\u201d<\/strong> (Figure 4).<\/p>\n\n\n\n
![\"\"](\"https:\/\/i0.wp.com\/www.foxquestsystems.net\/foxblog\/wp-content\/uploads\/2026\/09\/rpt15-nssp-1.png?fit=980%2C266&ssl=1\")
Figure 4<\/figcaption><\/figure>\n\n\n\n Conclusion<\/strong><\/h2>\n\n\n\n
In a CPM network, logic should flow through every task like water through a pipe. During the forward pass, at least one relationship must carry logic into the start and out of the finish of each task. During the backward pass, at least one relationship must carry logic into the finish and out of the start of each task. Checking both conditions helps confirm\u2014although it does not guarantee\u2014that the CPM network conforms to industry best practice rules and guidelines.<\/p>\n\n\n\n
\u00a92026 FoxQuest Systems, Inc. All Rights Reserved<\/p>\n","protected":false},"excerpt":{"rendered":"
Introduction The Precedence Diagram Method (PDM) provides several ways to define relationships between activities. However, schedulers may incorrectly use these options in ways that allow logic to bypass one end of an activity. Two common examples: These two patterns mirror each other, so this article covers both. It explains: Case 1: No Finish-Side Successor In … Continue reading “Hidden Open Ends: No Finish Side Successor\/No Start Side Predecessor”<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":2286,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"nf_dc_page":"","om_disable_all_campaigns":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":false},"categories":[2,12],"tags":[],"class_list":["post-2277","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-analysis","category-tips"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"https:\/\/i0.wp.com\/www.foxquestsystems.net\/foxblog\/wp-content\/uploads\/2026\/09\/no-fss-ssp-feature-1.png?fit=446%2C223&ssl=1","_links":{"self":[{"href":"https:\/\/www.foxquestsystems.net\/foxblog\/wp-json\/wp\/v2\/posts\/2277","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.foxquestsystems.net\/foxblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.foxquestsystems.net\/foxblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.foxquestsystems.net\/foxblog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.foxquestsystems.net\/foxblog\/wp-json\/wp\/v2\/comments?post=2277"}],"version-history":[{"count":2,"href":"https:\/\/www.foxquestsystems.net\/foxblog\/wp-json\/wp\/v2\/posts\/2277\/revisions"}],"predecessor-version":[{"id":2287,"href":"https:\/\/www.foxquestsystems.net\/foxblog\/wp-json\/wp\/v2\/posts\/2277\/revisions\/2287"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.foxquestsystems.net\/foxblog\/wp-json\/wp\/v2\/media\/2286"}],"wp:attachment":[{"href":"https:\/\/www.foxquestsystems.net\/foxblog\/wp-json\/wp\/v2\/media?parent=2277"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.foxquestsystems.net\/foxblog\/wp-json\/wp\/v2\/categories?post=2277"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.foxquestsystems.net\/foxblog\/wp-json\/wp\/v2\/tags?post=2277"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
- OD of 32 to 41 days:<\/strong> Task D\u2019s TF value decreases, but no other activity\u2019s dates change.<\/li>\n\n\n\n
- OD of 17 to 22 days:<\/strong> Task D\u2019s TF value decreases, but Task F\u2019s start and finish dates do not change.<\/li>\n\n\n\n
- OD from 10 to 12 days:<\/strong> Task D\u2019s Total Float (TF) does not change.<\/li>\n\n\n\n