Here’s Lookin’

Here’s Lookin’ @ You, Niño #casablanca 1942-11_26 🙂
heres-lookin-you-nino-casablanca-1942-11_26

By default that slug is version of the post’s title, processed by WordPress to use only lower-case alphanumeric characters, also underscore and the dash (if not at the beginning or end of the title). WordPress takes the title and:
* Converts upper-case letters to lower-case.
* Converts accented letters to their unaccented equivalent.
* Removes all punctuation and symbols, except underscore and dash.
* Removes leading and trailing dash.
* Replaces space(s) with a dash.

So a slug allows lower-case alphanumeric characters, underscore, and dash ([a-z], [0-9], [_], [-]).
* Allow underscore (_),
* Allow dash (-), unless leading or trailing.

title, slug, and (working) permalink:
12345678901234567890123456789012345678901234567890123456789012345678901234567890
12345678901234567890123456789012345678901234567890123456789012345678901234567890
https://dev.pubmedia.us/2012/01/
12345678901234567890123456789012345678901234567890123456789012345678901234567890/

Page slugs shouldn’t be numeric-only.

http://core.trac.wordpress.org/ticket/14238

Here’s Lookin’@You,_Niño #casablanca 1942/11/26 🙂
heres-lookinyou_nino-casablanca-19421126

Here’s Lookin’@-You,_Niño #casablanca 1942/11/26 🙂
heres-lookinyou_nino-casablanca-19421126

Here’s Lookin’ @ You,_Niño #casablanca 1942/11/26 🙂
heres-lookin-you_nino-casablanca-19421126

Here’s Lookin’ @ You, Niño #casablanca 1942/11_26 🙂
heres-lookin-you-nino-casablanca-194211_26